mirror of
https://github.com/lightningnetwork/lnd.git
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htlcswitch: add new method handlePacketAdd
Simply moves the code into a new method so it's easier to follow the method `handlePacketForward`.
This commit is contained in:
yyforyongyu
yyforyongyu
parent
d28d5d7a47
commit
6cb374aea6
1 changed files with 178 additions and 179 deletions
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@ -1104,185 +1104,7 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
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// payment circuit within our internal state so we can properly forward
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// payment circuit within our internal state so we can properly forward
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// the ultimate settle message back latter.
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// the ultimate settle message back latter.
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case *lnwire.UpdateAddHTLC:
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case *lnwire.UpdateAddHTLC:
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// Check if the node is set to reject all onward HTLCs and also make
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return s.handlePacketAdd(packet, htlc)
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// sure that HTLC is not from the source node.
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if s.cfg.RejectHTLC {
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failure := NewDetailedLinkError(
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&lnwire.FailChannelDisabled{},
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OutgoingFailureForwardsDisabled,
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)
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return s.failAddPacket(packet, failure)
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}
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// Before we attempt to find a non-strict forwarding path for
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// this htlc, check whether the htlc is being routed over the
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// same incoming and outgoing channel. If our node does not
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// allow forwards of this nature, we fail the htlc early. This
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// check is in place to disallow inefficiently routed htlcs from
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// locking up our balance. With channels where the
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// option-scid-alias feature was negotiated, we also have to be
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// sure that the IDs aren't the same since one or both could be
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// an alias.
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linkErr := s.checkCircularForward(
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packet.incomingChanID, packet.outgoingChanID,
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s.cfg.AllowCircularRoute, htlc.PaymentHash,
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)
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if linkErr != nil {
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return s.failAddPacket(packet, linkErr)
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}
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s.indexMtx.RLock()
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targetLink, err := s.getLinkByMapping(packet)
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if err != nil {
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s.indexMtx.RUnlock()
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log.Debugf("unable to find link with "+
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"destination %v", packet.outgoingChanID)
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// If packet was forwarded from another channel link
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// than we should notify this link that some error
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// occurred.
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linkError := NewLinkError(
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&lnwire.FailUnknownNextPeer{},
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)
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return s.failAddPacket(packet, linkError)
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}
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targetPeerKey := targetLink.PeerPubKey()
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interfaceLinks, _ := s.getLinks(targetPeerKey)
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s.indexMtx.RUnlock()
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// We'll keep track of any HTLC failures during the link
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// selection process. This way we can return the error for
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// precise link that the sender selected, while optimistically
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// trying all links to utilize our available bandwidth.
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linkErrs := make(map[lnwire.ShortChannelID]*LinkError)
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// Find all destination channel links with appropriate
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// bandwidth.
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var destinations []ChannelLink
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for _, link := range interfaceLinks {
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var failure *LinkError
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// We'll skip any links that aren't yet eligible for
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// forwarding.
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if !link.EligibleToForward() {
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failure = NewDetailedLinkError(
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&lnwire.FailUnknownNextPeer{},
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OutgoingFailureLinkNotEligible,
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)
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} else {
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// We'll ensure that the HTLC satisfies the
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// current forwarding conditions of this target
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// link.
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currentHeight := atomic.LoadUint32(&s.bestHeight)
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failure = link.CheckHtlcForward(
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htlc.PaymentHash, packet.incomingAmount,
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packet.amount, packet.incomingTimeout,
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packet.outgoingTimeout,
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packet.inboundFee,
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currentHeight,
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packet.originalOutgoingChanID,
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)
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}
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// If this link can forward the htlc, add it to the set
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// of destinations.
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if failure == nil {
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destinations = append(destinations, link)
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continue
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}
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linkErrs[link.ShortChanID()] = failure
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}
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// If we had a forwarding failure due to the HTLC not
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// satisfying the current policy, then we'll send back an
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// error, but ensure we send back the error sourced at the
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// *target* link.
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if len(destinations) == 0 {
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// At this point, some or all of the links rejected the
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// HTLC so we couldn't forward it. So we'll try to look
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// up the error that came from the source.
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linkErr, ok := linkErrs[packet.outgoingChanID]
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if !ok {
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// If we can't find the error of the source,
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// then we'll return an unknown next peer,
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// though this should never happen.
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linkErr = NewLinkError(
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&lnwire.FailUnknownNextPeer{},
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)
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log.Warnf("unable to find err source for "+
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"outgoing_link=%v, errors=%v",
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packet.outgoingChanID,
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lnutils.SpewLogClosure(linkErrs))
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}
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log.Tracef("incoming HTLC(%x) violated "+
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"target outgoing link (id=%v) policy: %v",
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htlc.PaymentHash[:], packet.outgoingChanID,
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linkErr)
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return s.failAddPacket(packet, linkErr)
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}
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// Choose a random link out of the set of links that can forward
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// this htlc. The reason for randomization is to evenly
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// distribute the htlc load without making assumptions about
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// what the best channel is.
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destination := destinations[rand.Intn(len(destinations))] // nolint:gosec
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// Retrieve the incoming link by its ShortChannelID. Note that
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// the incomingChanID is never set to hop.Source here.
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s.indexMtx.RLock()
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incomingLink, err := s.getLinkByShortID(packet.incomingChanID)
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s.indexMtx.RUnlock()
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if err != nil {
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// If we couldn't find the incoming link, we can't
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// evaluate the incoming's exposure to dust, so we just
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// fail the HTLC back.
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linkErr := NewLinkError(
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&lnwire.FailTemporaryChannelFailure{},
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)
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return s.failAddPacket(packet, linkErr)
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}
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// Evaluate whether this HTLC would increase our fee exposure
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// over the threshold on the incoming link. If it does, fail it
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// backwards.
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if s.dustExceedsFeeThreshold(
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incomingLink, packet.incomingAmount, true,
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) {
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// The incoming dust exceeds the threshold, so we fail
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// the add back.
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linkErr := NewLinkError(
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&lnwire.FailTemporaryChannelFailure{},
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)
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return s.failAddPacket(packet, linkErr)
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}
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// Also evaluate whether this HTLC would increase our fee
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// exposure over the threshold on the destination link. If it
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// does, fail it back.
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if s.dustExceedsFeeThreshold(
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destination, packet.amount, false,
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) {
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// The outgoing dust exceeds the threshold, so we fail
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// the add back.
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linkErr := NewLinkError(
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&lnwire.FailTemporaryChannelFailure{},
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)
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return s.failAddPacket(packet, linkErr)
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}
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// Send the packet to the destination channel link which
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// manages the channel.
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packet.outgoingChanID = destination.ShortChanID()
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return destination.handleSwitchPacket(packet)
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case *lnwire.UpdateFailHTLC, *lnwire.UpdateFulfillHTLC:
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case *lnwire.UpdateFailHTLC, *lnwire.UpdateFulfillHTLC:
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// If the source of this packet has not been set, use the
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// If the source of this packet has not been set, use the
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@ -3052,3 +2874,180 @@ func (s *Switch) AddAliasForLink(chanID lnwire.ChannelID,
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return nil
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return nil
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}
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}
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// handlePacketAdd handles forwarding an Add packet.
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func (s *Switch) handlePacketAdd(packet *htlcPacket,
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htlc *lnwire.UpdateAddHTLC) error {
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// Check if the node is set to reject all onward HTLCs and also make
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// sure that HTLC is not from the source node.
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if s.cfg.RejectHTLC {
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failure := NewDetailedLinkError(
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&lnwire.FailChannelDisabled{},
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OutgoingFailureForwardsDisabled,
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)
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return s.failAddPacket(packet, failure)
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}
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// Before we attempt to find a non-strict forwarding path for this
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// htlc, check whether the htlc is being routed over the same incoming
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// and outgoing channel. If our node does not allow forwards of this
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// nature, we fail the htlc early. This check is in place to disallow
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// inefficiently routed htlcs from locking up our balance. With
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// channels where the option-scid-alias feature was negotiated, we also
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// have to be sure that the IDs aren't the same since one or both could
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// be an alias.
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linkErr := s.checkCircularForward(
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packet.incomingChanID, packet.outgoingChanID,
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s.cfg.AllowCircularRoute, htlc.PaymentHash,
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)
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if linkErr != nil {
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return s.failAddPacket(packet, linkErr)
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}
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s.indexMtx.RLock()
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targetLink, err := s.getLinkByMapping(packet)
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if err != nil {
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s.indexMtx.RUnlock()
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log.Debugf("unable to find link with "+
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"destination %v", packet.outgoingChanID)
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// If packet was forwarded from another channel link than we
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// should notify this link that some error occurred.
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linkError := NewLinkError(
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&lnwire.FailUnknownNextPeer{},
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)
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return s.failAddPacket(packet, linkError)
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}
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targetPeerKey := targetLink.PeerPubKey()
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interfaceLinks, _ := s.getLinks(targetPeerKey)
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s.indexMtx.RUnlock()
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// We'll keep track of any HTLC failures during the link selection
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// process. This way we can return the error for precise link that the
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// sender selected, while optimistically trying all links to utilize
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// our available bandwidth.
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linkErrs := make(map[lnwire.ShortChannelID]*LinkError)
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// Find all destination channel links with appropriate bandwidth.
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var destinations []ChannelLink
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for _, link := range interfaceLinks {
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var failure *LinkError
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// We'll skip any links that aren't yet eligible for
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// forwarding.
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if !link.EligibleToForward() {
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failure = NewDetailedLinkError(
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&lnwire.FailUnknownNextPeer{},
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OutgoingFailureLinkNotEligible,
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)
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} else {
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// We'll ensure that the HTLC satisfies the current
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// forwarding conditions of this target link.
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currentHeight := atomic.LoadUint32(&s.bestHeight)
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failure = link.CheckHtlcForward(
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htlc.PaymentHash, packet.incomingAmount,
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packet.amount, packet.incomingTimeout,
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packet.outgoingTimeout,
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packet.inboundFee,
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currentHeight,
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packet.originalOutgoingChanID,
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)
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}
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// If this link can forward the htlc, add it to the set of
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// destinations.
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if failure == nil {
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destinations = append(destinations, link)
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continue
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}
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linkErrs[link.ShortChanID()] = failure
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}
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// If we had a forwarding failure due to the HTLC not satisfying the
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// current policy, then we'll send back an error, but ensure we send
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// back the error sourced at the *target* link.
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if len(destinations) == 0 {
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// At this point, some or all of the links rejected the HTLC so
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// we couldn't forward it. So we'll try to look up the error
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// that came from the source.
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linkErr, ok := linkErrs[packet.outgoingChanID]
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if !ok {
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// If we can't find the error of the source, then we'll
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// return an unknown next peer, though this should
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// never happen.
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linkErr = NewLinkError(
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&lnwire.FailUnknownNextPeer{},
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)
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log.Warnf("unable to find err source for "+
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"outgoing_link=%v, errors=%v",
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packet.outgoingChanID,
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lnutils.SpewLogClosure(linkErrs))
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}
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log.Tracef("incoming HTLC(%x) violated "+
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"target outgoing link (id=%v) policy: %v",
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htlc.PaymentHash[:], packet.outgoingChanID,
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linkErr)
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return s.failAddPacket(packet, linkErr)
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}
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// Choose a random link out of the set of links that can forward this
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// htlc. The reason for randomization is to evenly distribute the htlc
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// load without making assumptions about what the best channel is.
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destination := destinations[rand.Intn(len(destinations))] // nolint:gosec
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// Retrieve the incoming link by its ShortChannelID. Note that the
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// incomingChanID is never set to hop.Source here.
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s.indexMtx.RLock()
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incomingLink, err := s.getLinkByShortID(packet.incomingChanID)
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s.indexMtx.RUnlock()
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if err != nil {
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// If we couldn't find the incoming link, we can't evaluate the
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// incoming's exposure to dust, so we just fail the HTLC back.
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linkErr := NewLinkError(
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&lnwire.FailTemporaryChannelFailure{},
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)
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return s.failAddPacket(packet, linkErr)
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}
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// Evaluate whether this HTLC would increase our fee exposure over the
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// threshold on the incoming link. If it does, fail it backwards.
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if s.dustExceedsFeeThreshold(
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incomingLink, packet.incomingAmount, true,
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) {
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// The incoming dust exceeds the threshold, so we fail the add
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// back.
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linkErr := NewLinkError(
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&lnwire.FailTemporaryChannelFailure{},
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)
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return s.failAddPacket(packet, linkErr)
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}
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// Also evaluate whether this HTLC would increase our fee exposure over
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// the threshold on the destination link. If it does, fail it back.
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if s.dustExceedsFeeThreshold(
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destination, packet.amount, false,
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) {
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// The outgoing dust exceeds the threshold, so we fail the add
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// back.
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linkErr := NewLinkError(
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&lnwire.FailTemporaryChannelFailure{},
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)
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return s.failAddPacket(packet, linkErr)
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}
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// Send the packet to the destination channel link which manages the
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// channel.
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packet.outgoingChanID = destination.ShortChanID()
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return destination.handleSwitchPacket(packet)
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}
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Add table
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