common

Documentation

Index

• type AddRef
• type ChannelCloseSummary
• type ChannelCommitment
• type ChannelConfig
• type ChannelConstraints
• type CircuitKey
• type ClosureType
• type CommitDiff
• type FwdPkg
  • func NewFwdPkg(source lnwire.ShortChannelID, height uint64, ...) *FwdPkg
• type FwdState
• type HTLC
• type LogUpdate
• type NetworkResult
• type PkgFilter
  • func NewPkgFilter(count uint16) *PkgFilter
  • func (f *PkgFilter) Contains(i uint16) bool
  • func (f *PkgFilter) Count() uint16
  • func (f *PkgFilter) Decode(r io.Reader) error
  • func (f *PkgFilter) Encode(w io.Writer) error
  • func (f *PkgFilter) Equal(f2 *PkgFilter) bool
  • func (f *PkgFilter) IsFull() bool
  • func (f *PkgFilter) Set(i uint16)
  • func (f *PkgFilter) Size() uint16
• type SettleFailRef

Types

type AddRef

type AddRef struct {
	// Height is the remote commitment height that locked in the Add.
	Height uint64

	// Index is the index of the Add within the fwd pkg's Adds.
	//
	// NOTE: This index is static over the lifetime of a forwarding package.
	Index uint16
}

AddRef is used to identify a particular Add in a FwdPkg. The short channel ID is assumed to be that of the packager.

type ChannelCloseSummary

type ChannelCloseSummary struct {
	// ChanPoint is the outpoint for this channel's funding transaction,
	// and is used as a unique identifier for the channel.
	ChanPoint wire.OutPoint

	// ShortChanID encodes the exact location in the chain in which the
	// channel was initially confirmed. This includes: the block height,
	// transaction index, and the output within the target transaction.
	ShortChanID lnwire.ShortChannelID

	// ChainHash is the hash of the genesis block that this channel resides
	// within.
	ChainHash chainhash.Hash

	// ClosingTXID is the txid of the transaction which ultimately closed
	// this channel.
	ClosingTXID chainhash.Hash

	// RemotePub is the public key of the remote peer that we formerly had
	// a channel with.
	RemotePub *secp256k1.PublicKey

	// Capacity was the total capacity of the channel.
	Capacity dcrutil.Amount

	// CloseHeight is the height at which the funding transaction was
	// spent.
	CloseHeight uint32

	// SettledBalance is our total balance settled balance at the time of
	// channel closure. This _does not_ include the sum of any outputs that
	// have been time-locked as a result of the unilateral channel closure.
	SettledBalance dcrutil.Amount

	// TimeLockedBalance is the sum of all the time-locked outputs at the
	// time of channel closure. If we triggered the force closure of this
	// channel, then this value will be non-zero if our settled output is
	// above the dust limit. If we were on the receiving side of a channel
	// force closure, then this value will be non-zero if we had any
	// outstanding outgoing HTLC's at the time of channel closure.
	TimeLockedBalance dcrutil.Amount

	// CloseType details exactly _how_ the channel was closed. Five closure
	// types are possible: cooperative, local force, remote force, breach
	// and funding canceled.
	CloseType ClosureType

	// IsPending indicates whether this channel is in the 'pending close'
	// state, which means the channel closing transaction has been
	// confirmed, but not yet been fully resolved. In the case of a channel
	// that has been cooperatively closed, it will go straight into the
	// fully resolved state as soon as the closing transaction has been
	// confirmed. However, for channels that have been force closed, they'll
	// stay marked as "pending" until _all_ the pending funds have been
	// swept.
	IsPending bool

	// RemoteCurrentRevocation is the current revocation for their
	// commitment transaction. However, since this is the derived public key,
	// we don't yet have the private key so we aren't yet able to verify
	// that it's actually in the hash chain.
	RemoteCurrentRevocation *secp256k1.PublicKey

	// RemoteNextRevocation is the revocation key to be used for the *next*
	// commitment transaction we create for the local node. Within the
	// specification, this value is referred to as the
	// per-commitment-point.
	RemoteNextRevocation *secp256k1.PublicKey

	// LocalChanCfg is the channel configuration for the local node.
	LocalChanConfig ChannelConfig

	// LastChanSyncMsg is the ChannelReestablish message for this channel
	// for the state at the point where it was closed.
	LastChanSyncMsg *lnwire.ChannelReestablish
}

ChannelCloseSummary contains the final state of a channel at the point it was closed. Once a channel is closed, all the information pertaining to that channel within the openChannelBucket is deleted, and a compact summary is put in place instead.

type ChannelCommitment

type ChannelCommitment struct {
	// CommitHeight is the update number that this ChannelDelta represents
	// the total number of commitment updates to this point. This can be
	// viewed as sort of a "commitment height" as this number is
	// monotonically increasing.
	CommitHeight uint64

	// LocalLogIndex is the cumulative log index index of the local node at
	// this point in the commitment chain. This value will be incremented
	// for each _update_ added to the local update log.
	LocalLogIndex uint64

	// LocalHtlcIndex is the current local running HTLC index. This value
	// will be incremented for each outgoing HTLC the local node offers.
	LocalHtlcIndex uint64

	// RemoteLogIndex is the cumulative log index index of the remote node
	// at this point in the commitment chain. This value will be
	// incremented for each _update_ added to the remote update log.
	RemoteLogIndex uint64

	// RemoteHtlcIndex is the current remote running HTLC index. This value
	// will be incremented for each outgoing HTLC the remote node offers.
	RemoteHtlcIndex uint64

	// LocalBalance is the current available settled balance within the
	// channel directly spendable by us.
	//
	// NOTE: This is the balance *after* subtracting any commitment fee,
	// AND anchor output values.
	LocalBalance lnwire.MilliAtom

	// RemoteBalance is the current available settled balance within the
	// channel directly spendable by the remote node.
	//
	// NOTE: This is the balance *after* subtracting any commitment fee,
	// AND anchor output values.
	RemoteBalance lnwire.MilliAtom

	// CommitFee is the amount calculated to be paid in fees for the
	// current set of commitment transactions. The fee amount is persisted
	// with the channel in order to allow the fee amount to be removed and
	// recalculated with each channel state update, including updates that
	// happen after a system restart.
	CommitFee dcrutil.Amount

	// FeePerKB is the min atoms/kilobyte that should be paid within the
	// commitment transaction for the entire duration of the channel's
	// lifetime. This field may be updated during normal operation of the
	// channel as on-chain conditions change.
	//
	// TODO(halseth): make this AtomsPerKByte. Cannot be done atm because
	// this will cause the import cycle lnwallet<->channeldb. Fee
	// estimation stuff should be in its own package.
	FeePerKB dcrutil.Amount

	// CommitTx is the latest version of the commitment state, broadcast
	// able by us.
	CommitTx *wire.MsgTx

	// CommitSig is one half of the signature required to fully complete
	// the script for the commitment transaction above. This is the
	// signature signed by the remote party for our version of the
	// commitment transactions.
	CommitSig []byte

	// Htlcs is the set of HTLC's that are pending at this particular
	// commitment height.
	Htlcs []HTLC
}

ChannelCommitment is a snapshot of the commitment state at a particular point in the commitment chain. With each state transition, a snapshot of the current state along with all non-settled HTLCs are recorded. These snapshots detail the state of the _remote_ party's commitment at a particular state number. For ourselves (the local node) we ONLY store our most recent (unrevoked) state for safety purposes.

type ChannelConfig

type ChannelConfig struct {
	// ChannelConstraints is the set of constraints that must be upheld for
	// the duration of the channel for the owner of this channel
	// configuration. Constraints govern a number of flow control related
	// parameters, also including the smallest HTLC that will be accepted
	// by a participant.
	ChannelConstraints

	// MultiSigKey is the key to be used within the 2-of-2 output script
	// for the owner of this channel config.
	MultiSigKey keychain.KeyDescriptor

	// RevocationBasePoint is the base public key to be used when deriving
	// revocation keys for the remote node's commitment transaction. This
	// will be combined along with a per commitment secret to derive a
	// unique revocation key for each state.
	RevocationBasePoint keychain.KeyDescriptor

	// PaymentBasePoint is the base public key to be used when deriving
	// the key used within the non-delayed pay-to-self output on the
	// commitment transaction for a node. This will be combined with a
	// tweak derived from the per-commitment point to ensure unique keys
	// for each commitment transaction.
	PaymentBasePoint keychain.KeyDescriptor

	// DelayBasePoint is the base public key to be used when deriving the
	// key used within the delayed pay-to-self output on the commitment
	// transaction for a node. This will be combined with a tweak derived
	// from the per-commitment point to ensure unique keys for each
	// commitment transaction.
	DelayBasePoint keychain.KeyDescriptor

	// HtlcBasePoint is the base public key to be used when deriving the
	// local HTLC key. The derived key (combined with the tweak derived
	// from the per-commitment point) is used within the "to self" clause
	// within any HTLC output scripts.
	HtlcBasePoint keychain.KeyDescriptor
}

ChannelConfig is a struct that houses the various configuration opens for channels. Each side maintains an instance of this configuration file as it governs: how the funding and commitment transaction to be created, the nature of HTLC's allotted, the keys to be used for delivery, and relative time lock parameters.

type ChannelConstraints

type ChannelConstraints struct {
	// DustLimit is the threhsold (in atoms) below which any outputs
	// should be trimmed. When an output is trimmed, it isn't materialized
	// as an actual output, but is instead burned to miner's fees.
	DustLimit dcrutil.Amount

	// ChanReserve is an absolute reservation on the channel for the
	// owner of this set of constraints. This means that the current
	// settled balance for this node CANNOT dip below the reservation
	// amount. This acts as a defense against costless attacks when
	// either side no longer has any skin in the game.
	ChanReserve dcrutil.Amount

	// MaxPendingAmount is the maximum pending HTLC value that the
	// owner of these constraints can offer the remote node at a
	// particular time.
	MaxPendingAmount lnwire.MilliAtom

	// MinHTLC is the minimum HTLC value that the owner of these
	// constraints can offer the remote node. If any HTLCs below this
	// amount are offered, then the HTLC will be rejected. This, in
	// tandem with the dust limit allows a node to regulate the
	// smallest HTLC that it deems economically relevant.
	MinHTLC lnwire.MilliAtom

	// MaxAcceptedHtlcs is the maximum number of HTLCs that the owner of
	// this set of constraints can offer the remote node. This allows each
	// node to limit their over all exposure to HTLCs that may need to be
	// acted upon in the case of a unilateral channel closure or a contract
	// breach.
	MaxAcceptedHtlcs uint16

	// CsvDelay is the relative time lock delay expressed in blocks. Any
	// settled outputs that pay to the owner of this channel configuration
	// MUST ensure that the delay branch uses this value as the relative
	// time lock. Similarly, any HTLC's offered by this node should use
	// this value as well.
	CsvDelay uint16
}

ChannelConstraints represents a set of constraints meant to allow a node to limit their exposure, enact flow control and ensure that all HTLCs are economically relevant. This struct will be mirrored for both sides of the channel, as each side will enforce various constraints that MUST be adhered to for the life time of the channel. The parameters for each of these constraints are static for the duration of the channel, meaning the channel must be torn down for them to change.

type CircuitKey

type CircuitKey struct {
	// ChanID is the short chanid indicating the HTLC's origin.
	//
	// NOTE: It is fine for this value to be blank, as this indicates a
	// locally-sourced payment.
	ChanID lnwire.ShortChannelID

	// HtlcID is the unique htlc index predominately assigned by links,
	// though can also be assigned by switch in the case of locally-sourced
	// payments.
	HtlcID uint64
}

CircuitKey is used by a channel to uniquely identify the HTLCs it receives from the switch, and is used to purge our in-memory state of HTLCs that have already been processed by a link. Two list of CircuitKeys are included in each CommitDiff to allow a link to determine which in-memory htlcs directed the opening and closing of circuits in the switch's circuit map.

type ClosureType

type ClosureType uint8

ClosureType is an enum like structure that details exactly _how_ a channel was closed. Three closure types are currently possible: none, cooperative, local force close, remote force close, and (remote) breach.

type CommitDiff

type CommitDiff struct {
	// ChannelCommitment is the full commitment state that one would arrive
	// at by applying the set of messages contained in the UpdateDiff to
	// the prior accepted commitment.
	Commitment ChannelCommitment

	// LogUpdates is the set of messages sent prior to the commitment state
	// transition in question. Upon reconnection, if we detect that they
	// don't have the commitment, then we re-send this along with the
	// proper signature.
	LogUpdates []LogUpdate

	// CommitSig is the exact CommitSig message that should be sent after
	// the set of LogUpdates above has been retransmitted. The signatures
	// within this message should properly cover the new commitment state
	// and also the HTLC's within the new commitment state.
	CommitSig *lnwire.CommitSig

	// OpenedCircuitKeys is a set of unique identifiers for any downstream
	// Add packets included in this commitment txn. After a restart, this
	// set of htlcs is acked from the link's incoming mailbox to ensure
	// there isn't an attempt to re-add them to this commitment txn.
	OpenedCircuitKeys []CircuitKey

	// ClosedCircuitKeys records the unique identifiers for any settle/fail
	// packets that were resolved by this commitment txn. After a restart,
	// this is used to ensure those circuits are removed from the circuit
	// map, and the downstream packets in the link's mailbox are removed.
	ClosedCircuitKeys []CircuitKey

	// AddAcks specifies the locations (commit height, pkg index) of any
	// Adds that were failed/settled in this commit diff. This will ack
	// entries in *this* channel's forwarding packages.
	//
	// NOTE: This value is not serialized, it is used to atomically mark the
	// resolution of adds, such that they will not be reprocessed after a
	// restart.
	AddAcks []AddRef

	// SettleFailAcks specifies the locations (chan id, commit height, pkg
	// index) of any Settles or Fails that were locked into this commit
	// diff, and originate from *another* channel, i.e. the outgoing link.
	//
	// NOTE: This value is not serialized, it is used to atomically acks
	// settles and fails from the forwarding packages of other channels,
	// such that they will not be reforwarded internally after a restart.
	SettleFailAcks []SettleFailRef
}

CommitDiff represents the delta needed to apply the state transition between two subsequent commitment states. Given state N and state N+1, one is able to apply the set of messages contained within the CommitDiff to N to arrive at state N+1. Each time a new commitment is extended, we'll write a new commitment (along with the full commitment state) to disk so we can re-transmit the state in the case of a connection loss or message drop.

type FwdPkg

type FwdPkg struct {
	// Source identifies the channel that wrote this forwarding package.
	Source lnwire.ShortChannelID

	// Height is the height of the remote commitment chain that locked in
	// this forwarding package.
	Height uint64

	// State signals the persistent condition of the package and directs how
	// to reprocess the package in the event of failures.
	State FwdState

	// Adds contains all add messages which need to be processed and
	// forwarded to the switch. Adds does not change over the life of a
	// forwarding package.
	Adds []LogUpdate

	// FwdFilter is a filter containing the indices of all Adds that were
	// forwarded to the switch.
	FwdFilter *PkgFilter

	// AckFilter is a filter containing the indices of all Adds for which
	// the source has received a settle or fail and is reflected in the next
	// commitment txn. A package should not be removed until IsFull()
	// returns true.
	AckFilter *PkgFilter

	// SettleFails contains all settle and fail messages that should be
	// forwarded to the switch.
	SettleFails []LogUpdate

	// SettleFailFilter is a filter containing the indices of all Settle or
	// Fails originating in this package that have been received and locked
	// into the incoming link's commitment state.
	SettleFailFilter *PkgFilter
}

FwdPkg records all adds, settles, and fails that were locked in as a result of the remote peer sending us a revocation. Each package is identified by the short chanid and remote commitment height corresponding to the revocation that locked in the HTLCs. For everything except a locally initiated payment, settles and fails in a forwarding package must have a corresponding Add in another package, and can be removed individually once the source link has received the fail/settle.

Adds cannot be removed, as we need to present the same batch of Adds to properly handle replay protection. Instead, we use a PkgFilter to mark that we have finished processing a particular Add. A FwdPkg should only be deleted after the AckFilter is full and all settles and fails have been persistently removed.

func NewFwdPkg

func NewFwdPkg(source lnwire.ShortChannelID, height uint64,
	addUpdates, settleFailUpdates []LogUpdate) *FwdPkg

NewFwdPkg initializes a new forwarding package in FwdStateLockedIn. This should be used to create a package at the time we receive a revocation.

type FwdState

type FwdState byte

FwdState is an enum used to describe the lifecycle of a FwdPkg.

const (
	// FwdStateLockedIn is the starting state for all forwarding packages.
	// Packages in this state have not yet committed to the exact set of
	// Adds to forward to the switch.
	FwdStateLockedIn FwdState = iota

	// FwdStateProcessed marks the state in which all Adds have been
	// locally processed and the forwarding decision to the switch has been
	// persisted.
	FwdStateProcessed

	// FwdStateCompleted signals that all Adds have been acked, and that all
	// settles and fails have been delivered to their sources. Packages in
	// this state can be removed permanently.
	FwdStateCompleted
)

type HTLC

type HTLC struct {
	// Signature is the signature for the second level covenant transaction
	// for this HTLC. The second level transaction is a timeout tx in the
	// case that this is an outgoing HTLC, and a success tx in the case
	// that this is an incoming HTLC.
	//
	// TODO(roasbeef): make [64]byte instead?
	Signature []byte

	// RHash is the payment hash of the HTLC.
	RHash [32]byte

	// Amt is the amount of milli-atoms this HTLC escrows.
	Amt lnwire.MilliAtom

	// RefundTimeout is the absolute timeout on the HTLC that the sender
	// must wait before reclaiming the funds in limbo.
	RefundTimeout uint32

	// OutputIndex is the output index for this particular HTLC output
	// within the commitment transaction.
	OutputIndex int32

	// Incoming denotes whether we're the receiver or the sender of this
	// HTLC.
	Incoming bool

	// OnionBlob is an opaque blob which is used to complete multi-hop
	// routing.
	OnionBlob []byte

	// HtlcIndex is the HTLC counter index of this active, outstanding
	// HTLC. This differs from the LogIndex, as the HtlcIndex is only
	// incremented for each offered HTLC, while they LogIndex is
	// incremented for each update (includes settle+fail).
	HtlcIndex uint64

	// LogIndex is the cumulative log index of this HTLC. This differs
	// from the HtlcIndex as this will be incremented for each new log
	// update added.
	LogIndex uint64
}

HTLC is the on-disk representation of a hash time-locked contract. HTLCs are contained within ChannelDeltas which encode the current state of the commitment between state updates.

TODO(roasbeef): save space by using smaller ints at tail end?

type LogUpdate

type LogUpdate struct {
	// LogIndex is the log index of this proposed commitment update entry.
	LogIndex uint64

	// UpdateMsg is the update message that was included within the our
	// local update log. The LogIndex value denotes the log index of this
	// update which will be used when restoring our local update log if
	// we're left with a dangling update on restart.
	UpdateMsg lnwire.Message
}

LogUpdate represents a pending update to the remote commitment chain. The log update may be an add, fail, or settle entry. We maintain this data in order to be able to properly retransmit our proposed state if necessary.

type NetworkResult

type NetworkResult struct {
	// Msg is the received result. This should be of type UpdateFulfillHTLC
	// or UpdateFailHTLC.
	Msg lnwire.Message

	// unencrypted indicates whether the failure encoded in the message is
	// unencrypted, and hence doesn't need to be decrypted.
	Unencrypted bool

	// IsResolution indicates whether this is a resolution message, in
	// which the failure reason might not be included.
	IsResolution bool
}

NetworkResult is the raw result received from the network after a payment attempt has been made. Since the switch doesn't always have the necessary data to decode the raw message, we store it together with some meta data, and decode it when the router query for the final result.

type PkgFilter

type PkgFilter struct {
	// contains filtered or unexported fields
}

PkgFilter is used to compactly represent a particular subset of the Adds in a forwarding package. Each filter is represented as a simple, statically-sized bitvector, where the elements are intended to be the indices of the Adds as they are written in the FwdPkg.

func NewPkgFilter

func NewPkgFilter(count uint16) *PkgFilter

NewPkgFilter initializes an empty PkgFilter supporting `count` elements.

func (*PkgFilter) Contains

func (f *PkgFilter) Contains(i uint16) bool

Contains queries the filter for membership of index `i`. NOTE: It is assumed that i is always less than count.

func (*PkgFilter) Count

func (f *PkgFilter) Count() uint16

Count returns the number of elements represented by this PkgFilter.

func (*PkgFilter) Decode

func (f *PkgFilter) Decode(r io.Reader) error

Decode reads the filter from the provided io.Reader.

func (*PkgFilter) Encode

func (f *PkgFilter) Encode(w io.Writer) error

Encode writes the filter to the provided io.Writer.

func (*PkgFilter) Equal

func (f *PkgFilter) Equal(f2 *PkgFilter) bool

Equal checks two PkgFilters for equality.

func (*PkgFilter) IsFull

func (f *PkgFilter) IsFull() bool

IsFull returns true if every element in the filter has been Set, and false otherwise.

func (*PkgFilter) Set

func (f *PkgFilter) Set(i uint16)

Set marks the `i`-th element as included by this filter. NOTE: It is assumed that i is always less than count.

func (*PkgFilter) Size

func (f *PkgFilter) Size() uint16

Size returns number of bytes produced when the PkgFilter is serialized.

type SettleFailRef

type SettleFailRef struct {
	// Source identifies the outgoing link that locked in the settle or
	// fail. This is then used by the *incoming* link to find the settle
	// fail in another link's forwarding packages.
	Source lnwire.ShortChannelID

	// Height is the remote commitment height that locked in this
	// Settle/Fail.
	Height uint64

	// Index is the index of the Add with the fwd pkg's SettleFails.
	//
	// NOTE: This index is static over the lifetime of a forwarding package.
	Index uint16
}

SettleFailRef is used to locate a Settle/Fail in another channel's FwdPkg. A channel does not remove its own Settle/Fail htlcs, so the source is provided to locate a db bucket belonging to another channel.