lnd.xprv/htlcswitch/packet.go

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package htlcswitch
import (
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/lnwire"
)
// htlcPacket is a wrapper around htlc lnwire update, which adds additional
// information which is needed by this package.
type htlcPacket struct {
// incomingChanID is the ID of the channel that we have received an incoming
// HTLC on.
incomingChanID lnwire.ShortChannelID
// outgoingChanID is the ID of the channel that we have offered or will
// offer an outgoing HTLC on.
outgoingChanID lnwire.ShortChannelID
// incomingHTLCID is the ID of the HTLC that we have received from the peer
// on the incoming channel.
incomingHTLCID uint64
// incomingHtlcAmt is the value of the *incoming* HTLC. This will be
// set by the link when it receives an incoming HTLC to be forwarded
// through the switch. Then the outgoing link will use this once it
// creates a full circuit add. This allows us to properly populate the
// forwarding event for this circuit/packet in the case the payment
// circuit is successful.
incomingHtlcAmt lnwire.MilliSatoshi
// outgoingHTLCID is the ID of the HTLC that we offered to the peer on the
// outgoing channel.
outgoingHTLCID uint64
// sourceRef is used by forwarded htlcPackets to locate incoming Add
// entry in a fwdpkg owned by the incoming link. This value can be nil
// if there is no such entry, e.g. switch initiated payments.
sourceRef *channeldb.AddRef
// destRef is used to locate a settle/fail entry in the outgoing link's
// fwdpkg. If sourceRef is non-nil, this reference should be to a
// settle/fail in response to the sourceRef.
destRef *channeldb.SettleFailRef
// incomingAmount is the value in milli-satoshis that arrived on an
// incoming link.
incomingAmount lnwire.MilliSatoshi
// amount is the value of the HTLC that is being created or modified.
amount lnwire.MilliSatoshi
// htlc lnwire message type of which depends on switch request type.
htlc lnwire.Message
// obfuscator contains the necessary state to allow the switch to wrap
// any forwarded errors in an additional layer of encryption.
obfuscator ErrorEncrypter
// localFailure is set to true if an HTLC fails for a local payment before
// the first hop. In this case, the failure reason is simply encoded, not
// encrypted with any shared secret.
localFailure bool
// convertedError is set to true if this is an HTLC fail that was
// created using an UpdateFailMalformedHTLC from the remote party. If
// this is true, then when forwarding this failure packet, we'll need
// to wrap it as if we were the first hop if it's a multi-hop HTLC. If
// it's a direct HTLC, then we'll decode the error as no encryption has
// taken place.
convertedError bool
// hasSource is set to true if the incomingChanID and incomingHTLCID
// fields of a forwarded fail packet are already set and do not need to
// be looked up in the circuit map.
hasSource bool
// isResolution is set to true if this packet was actually an incoming
// resolution message from an outside sub-system. We'll treat these as
// if they emanated directly from the switch. As a result, we'll
// encrypt all errors related to this packet as if we were the first
// hop.
isResolution bool
// circuit holds a reference to an Add's circuit which is persisted in
// the switch during successful forwarding.
circuit *PaymentCircuit
// incomingTimeout is the timeout that the incoming HTLC carried. This
// is the timeout of the HTLC applied to the incoming link.
incomingTimeout uint32
// outgoingTimeout is the timeout of the proposed outgoing HTLC. This
// will be extraced from the hop payload recevived by the incoming
// link.
outgoingTimeout uint32
}
// inKey returns the circuit key used to identify the incoming htlc.
func (p *htlcPacket) inKey() CircuitKey {
return CircuitKey{
ChanID: p.incomingChanID,
HtlcID: p.incomingHTLCID,
}
}
// outKey returns the circuit key used to identify the outgoing, forwarded htlc.
func (p *htlcPacket) outKey() CircuitKey {
return CircuitKey{
ChanID: p.outgoingChanID,
HtlcID: p.outgoingHTLCID,
}
}
// keystone returns a tuple containing the incoming and outgoing circuit keys.
func (p *htlcPacket) keystone() Keystone {
return Keystone{
InKey: p.inKey(),
OutKey: p.outKey(),
}
}