lnd/htlcswitch/packet.go

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package htlcswitch
import (
"crypto/sha256"
"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 {
// destNode is the first-hop destination of a local created HTLC add
// message.
destNode [33]byte
// payHash is the payment hash of the HTLC which was modified by either
// a settle or fail action.
//
// NOTE: This fields is initialized only in settle and fail packets.
payHash [sha256.Size]byte
// dest is the destination of this packet identified by the short
// channel ID of the target link.
dest lnwire.ShortChannelID
// src is the source of this packet identified by the short channel ID
// of the target link.
src lnwire.ShortChannelID
// 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.
//
// TODO(andrew.shvv) revisit after refactoring the way of returning
// errors inside the htlcswitch packet.
obfuscator Obfuscator
// isObfuscated is set to true if an error occurs as soon as the switch
// forwards a packet to the link. If so, and this is an error packet,
// then this allows the switch to avoid doubly encrypting the error.
//
// TODO(andrew.shvv) revisit after refactoring the way of returning
// errors inside the htlcswitch packet.
isObfuscated bool
}
// newInitPacket creates htlc switch add packet which encapsulates the add htlc
// request and additional information for proper forwarding over htlc switch.
func newInitPacket(destNode [33]byte, htlc *lnwire.UpdateAddHTLC) *htlcPacket {
return &htlcPacket{
destNode: destNode,
htlc: htlc,
}
}
// newAddPacket creates htlc switch add packet which encapsulates the add htlc
// request and additional information for proper forwarding over htlc switch.
func newAddPacket(src, dest lnwire.ShortChannelID,
htlc *lnwire.UpdateAddHTLC, obfuscator Obfuscator) *htlcPacket {
return &htlcPacket{
dest: dest,
src: src,
htlc: htlc,
obfuscator: obfuscator,
}
}
// newSettlePacket creates htlc switch ack/settle packet which encapsulates the
// settle htlc request which should be created and sent back by last hope in
// htlc path.
func newSettlePacket(src lnwire.ShortChannelID, htlc *lnwire.UpdateFufillHTLC,
payHash [sha256.Size]byte, amount lnwire.MilliSatoshi) *htlcPacket {
return &htlcPacket{
src: src,
payHash: payHash,
htlc: htlc,
amount: amount,
}
}
// newFailPacket creates htlc switch fail packet which encapsulates the fail
// htlc request which propagated back to the original hope who sent the htlc
// add request if something wrong happened on the path to the final
// destination.
func newFailPacket(src lnwire.ShortChannelID, htlc *lnwire.UpdateFailHTLC,
payHash [sha256.Size]byte, amount lnwire.MilliSatoshi,
isObfuscated bool) *htlcPacket {
return &htlcPacket{
src: src,
payHash: payHash,
htlc: htlc,
amount: amount,
isObfuscated: isObfuscated,
}
}