74122a0901
This commit modifies the channel state machine slightly to encode the current state number using 30-bits of the sequence number within the commitment transaction’s only input. Such a modification reduces up the processing time required to punish the counter party for breaching the contract established within the channel by broadcasting an older revoked state. This fixes #58 with a minor modification to what was originally suggested.
1788 lines
64 KiB
Go
1788 lines
64 KiB
Go
package lnwallet
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import (
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"bytes"
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"container/list"
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"fmt"
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"sync"
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"github.com/btcsuite/fastsha256"
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"github.com/davecgh/go-spew/spew"
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"github.com/lightningnetwork/lnd/chainntnfs"
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"github.com/lightningnetwork/lnd/channeldb"
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"github.com/lightningnetwork/lnd/lnwire"
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"github.com/roasbeef/btcd/btcec"
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"github.com/roasbeef/btcd/txscript"
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"github.com/roasbeef/btcd/wire"
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"github.com/roasbeef/btcutil"
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"github.com/roasbeef/btcutil/txsort"
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)
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var zeroHash wire.ShaHash
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var (
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ErrChanClosing = fmt.Errorf("channel is being closed, operation disallowed")
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ErrNoWindow = fmt.Errorf("unable to sign new commitment, the current" +
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" revocation window is exhausted")
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)
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const (
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// MaxPendingPayments is the max number of pending HTLC's permitted on
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// a channel.
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// TODO(roasbeef): make not random value + enforce
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// * should be tuned to account for max tx "cost"
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MaxPendingPayments = 100
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// InitialRevocationWindow is the number of unrevoked commitment
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// transactions allowed within the commitment chain. This value allows
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// a greater degree of desynchronization by allowing either parties to
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// extend the other's commitment chain non-interactively, and also
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// serves as a flow control mechanism to a degree.
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InitialRevocationWindow = 4
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)
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// channelState is an enum like type which represents the current state of a
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// particular channel.
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// TODO(roasbeef): actually update state
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type channelState uint8
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const (
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// channelPending indicates this channel is still going through the
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// funding workflow, and isn't yet open.
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channelPending channelState = iota
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// channelOpen represents an open, active channel capable of
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// sending/receiving HTLCs.
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channelOpen
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// channelClosing represents a channel which is in the process of being
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// closed.
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channelClosing
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// channelClosed represents a channel which has been fully closed. Note
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// that before a channel can be closed, ALL pending HTLC's must be
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// settled/removed.
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channelClosed
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// channelDispute indicates that an un-cooperative closure has been
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// detected within the channel.
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channelDispute
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// channelPendingPayment indicates that there a currently outstanding
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// HTLC's within the channel.
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channelPendingPayment
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)
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// PaymentHash represents the sha256 of a random value. This hash is used to
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// uniquely track incoming/outgoing payments within this channel, as well as
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// payments requested by the wallet/daemon.
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type PaymentHash [32]byte
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// UpdateType is the exact type of an entry within the shared HTLC log.
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type updateType uint8
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const (
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Add updateType = iota
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Timeout
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Settle
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)
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// PaymentDescriptor represents a commitment state update which either adds,
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// settles, or removes an HTLC. PaymentDescriptors encapsulate all necessary
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// meta-data w.r.t to an HTLC, and additional data pairing a settle message to
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// the original added HTLC.
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// TODO(roasbeef): LogEntry interface??
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// * need to separate attrs for cancel/add/settle
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type PaymentDescriptor struct {
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sync.RWMutex
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// RHash is the payment hash for this HTLC. The HTLC can be settled iff
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// the preimage to this hash is presented.
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RHash PaymentHash
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// RPreimage is the preimage that settles the HTLC pointed to wthin the
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// log by the ParentIndex.
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RPreimage PaymentHash
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// Timeout is the absolute timeout in blocks, afterwhich this HTLC
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// expires.
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Timeout uint32
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// Amount is the HTLC amount in satoshis.
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Amount btcutil.Amount
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// Index is the log entry number that his HTLC update has within the
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// log. Depending on if IsIncoming is true, this is either an entry the
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// remote party added, or one that we added locally.
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Index uint32
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// ParentIndex is the index of the log entry that this HTLC update
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// settles or times out.
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ParentIndex uint32
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// Payload is an opaque blob which is used to complete multi-hop routing.
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Payload []byte
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// Type denotes the exact type of the PaymentDescriptor. In the case of
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// a Timeout, or Settle type, then the Parent field will point into the
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// log to the HTLC being modified.
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EntryType updateType
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// addCommitHeight[Remote|Local] encodes the height of the commitment
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// which included this HTLC on either the remote or local commitment
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// chain. This value is used to determine when an HTLC is fully
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// "locked-in".
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addCommitHeightRemote uint64
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addCommitHeightLocal uint64
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// removeCommitHeight[Remote|Local] encodes the height of the
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//commitment which removed the parent pointer of this PaymentDescriptor
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//either due to a timeout or a settle. Once both these heights are
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//above the tail of both chains, the log entries can safely be removed.
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removeCommitHeightRemote uint64
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removeCommitHeightLocal uint64
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// isForwarded denotes if an incoming HTLC has been forwarded to any
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// possible upstream peers in the route.
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isForwarded bool
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settled bool
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}
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// commitment represents a commitment to a new state within an active channel.
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// New commitments can be initiated by either side. Commitments are ordered
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// into a commitment chain, with one existing for both parties. Each side can
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// independently extend the other side's commitment chain, up to a certain
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// "revocation window", which once reached, disallows new commitments until
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// the local nodes receives the revocation for the remote node's chain tail.
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type commitment struct {
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// height represents the commitment height of this commitment, or the
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// update number of this commitment.
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height uint64
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// [our|their]MessageIndex are indexes into the HTLC log, up to which
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// this commitment transaction includes. These indexes allow both sides
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// to independently, and concurrent send create new commitments. Each
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// new commitment sent to the remote party includes an index in the
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// shared log which details which of their updates we're including in
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// this new commitment.
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// TODO(roasbeef): also make uint64?
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ourMessageIndex uint32
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theirMessageIndex uint32
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// txn is the commitment transaction generated by including any HTLC
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// updates whose index are below the two indexes listed above. If this
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// commitment is being added to the remote chain, then this txn is
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// their version of the commitment transactions. If the local commit
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// chain is being modified, the opposite is true.
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txn *wire.MsgTx
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// sig is a signature for the above commitment transaction.
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sig []byte
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// [our|their]Balance represents the settled balances at this point
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// within the commitment chain. This balance is computed by properly
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// evaluating all the add/remove/settle log entries before the listed
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// indexes.
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ourBalance btcutil.Amount
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theirBalance btcutil.Amount
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// htlcs is the set of HTLC's which remain unsettled within this
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// commitment.
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outgoingHTLCs []*PaymentDescriptor
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incomingHTLCs []*PaymentDescriptor
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}
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// toChannelDelta converts the target commitment into a format suitable to be
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// written to disk after an accepted state transition.
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// TODO(roasbeef): properly fill in refund timeouts
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func (c *commitment) toChannelDelta() (*channeldb.ChannelDelta, error) {
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numHtlcs := len(c.outgoingHTLCs) + len(c.incomingHTLCs)
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delta := &channeldb.ChannelDelta{
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LocalBalance: c.ourBalance,
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RemoteBalance: c.theirBalance,
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UpdateNum: uint32(c.height),
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Htlcs: make([]*channeldb.HTLC, 0, numHtlcs),
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}
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for _, htlc := range c.outgoingHTLCs {
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h := &channeldb.HTLC{
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Incoming: false,
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Amt: htlc.Amount,
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RHash: htlc.RHash,
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RefundTimeout: htlc.Timeout,
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RevocationDelay: 0,
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}
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delta.Htlcs = append(delta.Htlcs, h)
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}
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for _, htlc := range c.incomingHTLCs {
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h := &channeldb.HTLC{
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Incoming: true,
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Amt: htlc.Amount,
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RHash: htlc.RHash,
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RefundTimeout: htlc.Timeout,
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RevocationDelay: 0,
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}
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delta.Htlcs = append(delta.Htlcs, h)
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}
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return delta, nil
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}
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// commitmentChain represents a chain of unrevoked commitments. The tail of the
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// chain is the latest fully signed, yet unrevoked commitment. Two chains are
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// tracked, one for the local node, and another for the remote node. New
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// commitments we create locally extend the remote node's chain, and vice
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// versa. Commitment chains are allowed to grow to a bounded length, after
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// which the tail needs to be "dropped" before new commitments can be received.
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// The tail is "dropped" when the owner of the chain sends a revocation for the
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// previous tail.
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type commitmentChain struct {
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// commitments is a linked list of commitments to new states. New
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// commitments are added to the end of the chain with increase height.
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// Once a commitment transaction is revoked, the tail is incremented,
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// freeing up the revocation window for new commitments.
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commitments *list.List
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// startingHeight is the starting height of this commitment chain on a
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// session basis.
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startingHeight uint64
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}
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// newCommitmentChain creates a new commitment chain from an initial height.
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func newCommitmentChain(initialHeight uint64) *commitmentChain {
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return &commitmentChain{
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commitments: list.New(),
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startingHeight: initialHeight,
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}
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}
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// addCommitment extends the commitment chain by a single commitment. This
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// added commitment represents a state update propsed by either party. Once the
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// commitment prior to this commitment is revoked, the commitment becomes the
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// new defacto state within the channel.
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func (s *commitmentChain) addCommitment(c *commitment) {
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s.commitments.PushBack(c)
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}
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// advanceTail reduces the length of the commitment chain by one. The tail of
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// the chain should be advanced once a revocation for the lowest unrevoked
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// commitment in the chain is received.
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func (s *commitmentChain) advanceTail() {
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s.commitments.Remove(s.commitments.Front())
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}
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// tip returns the latest commitment added to the chain.
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func (s *commitmentChain) tip() *commitment {
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return s.commitments.Back().Value.(*commitment)
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}
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// tail returns the lowest unrevoked commitment transaction in the chain.
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func (s *commitmentChain) tail() *commitment {
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return s.commitments.Front().Value.(*commitment)
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}
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// LightningChannel implements the state machine which corresponds to the
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// current commitment protocol wire spec. The state machine implemented allows
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// for asynchronous fully desynchronized, batched+pipelined updates to
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// commitment transactions allowing for a high degree of non-blocking
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// bi-directional payment throughput.
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//
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// In order to allow updates to be fully non-blocking, either side is able to
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// create multiple new commitment states up to a pre-determined window size.
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// This window size is encoded within InitialRevocationWindow. Before the start
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// of a session, both side should send out revocation messages with nil
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// preimages in order to populate their revocation window for the remote party.
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// Ths method .ExtendRevocationWindow() is used to extend the revocation window
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// by a single revocation.
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//
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// The state machine has for main methods:
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// * .SignNextCommitment()
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// * Called one one wishes to sign the next commitment, either initiating a
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// new state update, or responding to a received commitment.
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// * .ReceiveNewCommitment()
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// * Called upon receipt of a new commitment from the remote party. If the
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// new commitment is valid, then a revocation should immediately be
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// generated and sent.
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// * .RevokeCurrentCommitment()
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// * Revokes the current commitment. Should be called directly after
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// receiving a new commitment.
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// * .ReceiveRevocation()
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// * Processes a revocation from the remote party. If successful creates a
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// new defacto broadcastable state.
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//
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// See the individual comments within the above methods for further details.
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type LightningChannel struct {
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signer Signer
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signDesc *SignDescriptor
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bio BlockChainIO
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channelEvents chainntnfs.ChainNotifier
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sync.RWMutex
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ourLogCounter uint32
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theirLogCounter uint32
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status channelState
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Capacity btcutil.Amount
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// currentHeight is the current height of our local commitment chain.
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// This is also the same as the number of updates to the channel we've
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// accepted.
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currentHeight uint64
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// revocationWindowEdge is the edge of the current revocation window.
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// New revocations for prior states created by this channel extend the
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// edge of this revocation window. The existence of a revocation window
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// allows the remote party to initiate new state updates independantly
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// until the window is exhausted.
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revocationWindowEdge uint64
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// usedRevocations is a slice of revocations given to us by the remote
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// party that we've used. This slice is extended each time we create a
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// new commitment. The front of the slice is popped off once we receive
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// a revocation for a prior state. This head element then becomes the
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// next set of keys/hashes we expect to be revoked.
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usedRevocations []*lnwire.CommitRevocation
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// revocationWindow is a window of revocations sent to use by the
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// remote party, allowing us to create new commitment transactions
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// until depleated. The revocations don't contain a valid pre-iamge,
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// only an additional key/hash allowing us to create a new commitment
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// transaction for the remote node that they are able to revoke. If
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// this slice is empty, then we cannot make any new updates to their
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// commitment chain.
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revocationWindow []*lnwire.CommitRevocation
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// remoteCommitChain is the remote node's commitment chain. Any new
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// commitments we initiate are added to the tip of this chain.
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remoteCommitChain *commitmentChain
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// localCommitChain is our local commitment chain. Any new commitments
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// received are added to the tip of this chain. The tail (or lowest
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// height) in this chain is our current accepted state, which we are
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// able to broadcast safely.
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localCommitChain *commitmentChain
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// stateMtx protects concurrent access to the state struct.
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stateMtx sync.RWMutex
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channelState *channeldb.OpenChannel
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// stateUpdateLog is a (mostly) append-only log storing all the HTLC
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// updates to this channel. The log is walked backwards as HTLC updates
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// are applied in order to re-construct a commitment transaction from a
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// commitment. The log is compacted once a revocation is received.
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ourUpdateLog *list.List
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theirUpdateLog *list.List
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// logIndex is an index into the above log. This index is used to
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// remove Add state updates, once a timeout/settle is received.
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ourLogIndex map[uint32]*list.Element
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theirLogIndex map[uint32]*list.Element
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LocalDeliveryScript []byte
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RemoteDeliveryScript []byte
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FundingWitnessScript []byte
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fundingTxIn *wire.TxIn
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fundingP2WSH []byte
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// ForceCloseSignal is a channel that is closed to indicate that a
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// local system has initiated a force close by broadcasting the current
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// commitment transaction directly on-chain.
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ForceCloseSignal chan struct{}
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// UnilateralCloseSignal is a channel that is closed to indicate that
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// the remote party has performed a unilateral close by broadcasting
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// their version of the commitment transaction on-chain.
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UnilateralCloseSignal chan struct{}
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started int32
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shutdown int32
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quit chan struct{}
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wg sync.WaitGroup
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}
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// NewLightningChannel creates a new, active payment channel given an
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// implementation of the chain notifier, channel database, and the current
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// settled channel state. Throughout state transitions, then channel will
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// automatically persist pertinent state to the database in an efficient
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// manner.
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func NewLightningChannel(signer Signer, bio BlockChainIO,
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events chainntnfs.ChainNotifier,
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state *channeldb.OpenChannel) (*LightningChannel, error) {
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// TODO(roasbeef): remove events+wallet
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lc := &LightningChannel{
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signer: signer,
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bio: bio,
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channelEvents: events,
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currentHeight: state.NumUpdates,
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remoteCommitChain: newCommitmentChain(state.NumUpdates),
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localCommitChain: newCommitmentChain(state.NumUpdates),
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channelState: state,
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revocationWindowEdge: state.NumUpdates,
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ourUpdateLog: list.New(),
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theirUpdateLog: list.New(),
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ourLogIndex: make(map[uint32]*list.Element),
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theirLogIndex: make(map[uint32]*list.Element),
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Capacity: state.Capacity,
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LocalDeliveryScript: state.OurDeliveryScript,
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RemoteDeliveryScript: state.TheirDeliveryScript,
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FundingWitnessScript: state.FundingWitnessScript,
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ForceCloseSignal: make(chan struct{}),
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UnilateralCloseSignal: make(chan struct{}),
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}
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// Initialize both of our chains the current un-revoked commitment for
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// each side.
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// TODO(roasbeef): add chnneldb.RevocationLogTail method, then init
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// their commitment from that as we may be de-synced
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initialCommitment := &commitment{
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height: lc.currentHeight,
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ourBalance: state.OurBalance,
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ourMessageIndex: 0,
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theirBalance: state.TheirBalance,
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theirMessageIndex: 0,
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}
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lc.localCommitChain.addCommitment(initialCommitment)
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lc.remoteCommitChain.addCommitment(initialCommitment)
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// If we're restarting from a channel with history, then restore the
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// update in-memory update logs to that of the prior state.
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if lc.currentHeight != 0 {
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lc.restoreStateLogs()
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}
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// Create the sign descriptor which we'll be using very frequently to
|
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// request a signature for the 2-of-2 multi-sig from the signer in
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// order to complete channel state transitions.
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fundingPkScript, err := witnessScriptHash(state.FundingWitnessScript)
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if err != nil {
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return nil, err
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}
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lc.fundingTxIn = wire.NewTxIn(state.FundingOutpoint, nil, nil)
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lc.fundingP2WSH = fundingPkScript
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lc.signDesc = &SignDescriptor{
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PubKey: lc.channelState.OurMultiSigKey,
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WitnessScript: lc.channelState.FundingWitnessScript,
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Output: &wire.TxOut{
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PkScript: lc.fundingP2WSH,
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Value: int64(lc.channelState.Capacity),
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},
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HashType: txscript.SigHashAll,
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InputIndex: 0,
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}
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// Register for a notification to be dispatched if the funding outpoint
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// has been spent. This indicates that either us or the remote party
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// has broadcasted a commitment transaction on-chain.
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fundingOut := &lc.fundingTxIn.PreviousOutPoint
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channelCloseNtfn, err := lc.channelEvents.RegisterSpendNtfn(fundingOut)
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if err != nil {
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return nil, err
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}
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// TODO(roasbeef) move into the peer's htlcManager?
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// * if not, send the SpendDetail over the channel instead of just
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// closing it
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go func() {
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// If the daemon is shutting down, then this notification channel
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// will be closed, so check the second read-value to avoid a false
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// positive.
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if _, ok := <-channelCloseNtfn.Spend; !ok {
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|
return
|
|
}
|
|
|
|
// TODO(roasbeef): only close channel if we detect that it's
|
|
// not our transaction?
|
|
|
|
// If the channel's doesn't already indicate that a commitment
|
|
// transaction has been broadcast on-chain, then this means the
|
|
// remote party broadcasted their commitment transaction.
|
|
// TODO(roasbeef): wait for a conf?
|
|
lc.Lock()
|
|
if lc.status != channelDispute {
|
|
close(lc.UnilateralCloseSignal)
|
|
lc.status = channelDispute
|
|
}
|
|
lc.Unlock()
|
|
}()
|
|
|
|
return lc, nil
|
|
}
|
|
|
|
// restoreStateLogs runs through the current locked-in HTLC's from the point of
|
|
// view of the channel and insert corresponding log entries (both local and
|
|
// remote) for each HTLC read from disk. This method is required sync the
|
|
// in-memory state of the state machine with that read from persistent storage.
|
|
func (lc *LightningChannel) restoreStateLogs() error {
|
|
var pastHeight uint64
|
|
if lc.currentHeight > 0 {
|
|
pastHeight = lc.currentHeight - 1
|
|
}
|
|
|
|
var ourCounter, theirCounter uint32
|
|
for _, htlc := range lc.channelState.Htlcs {
|
|
// TODO(roasbeef): set isForwarded to false for all? need to
|
|
// persist state w.r.t to if forwarded or not, or can
|
|
// inadvertenly trigger replays
|
|
pd := &PaymentDescriptor{
|
|
RHash: htlc.RHash,
|
|
Timeout: htlc.RefundTimeout,
|
|
Amount: htlc.Amt,
|
|
EntryType: Add,
|
|
addCommitHeightRemote: pastHeight,
|
|
addCommitHeightLocal: pastHeight,
|
|
}
|
|
|
|
if !htlc.Incoming {
|
|
pd.Index = ourCounter
|
|
lc.ourLogIndex[pd.Index] = lc.ourUpdateLog.PushBack(pd)
|
|
|
|
ourCounter++
|
|
} else {
|
|
pd.Index = theirCounter
|
|
lc.theirLogIndex[pd.Index] = lc.theirUpdateLog.PushBack(pd)
|
|
|
|
theirCounter++
|
|
}
|
|
}
|
|
|
|
lc.ourLogCounter = ourCounter
|
|
lc.theirLogCounter = theirCounter
|
|
|
|
lc.localCommitChain.tail().ourMessageIndex = ourCounter
|
|
lc.localCommitChain.tail().theirMessageIndex = theirCounter
|
|
lc.remoteCommitChain.tail().ourMessageIndex = ourCounter
|
|
lc.remoteCommitChain.tail().theirMessageIndex = theirCounter
|
|
|
|
return nil
|
|
}
|
|
|
|
type htlcView struct {
|
|
ourUpdates []*PaymentDescriptor
|
|
theirUpdates []*PaymentDescriptor
|
|
}
|
|
|
|
// fetchHTLCView returns all the candidate HTLC updates which should be
|
|
// considered for inclusion within a commitment based on the passed HTLC log
|
|
// indexes.
|
|
func (lc *LightningChannel) fetchHTLCView(theirLogIndex, ourLogIndex uint32) *htlcView {
|
|
var ourHTLCs []*PaymentDescriptor
|
|
for e := lc.ourUpdateLog.Front(); e != nil; e = e.Next() {
|
|
htlc := e.Value.(*PaymentDescriptor)
|
|
|
|
// This HTLC is active from this point-of-view iff the log
|
|
// index of the state update is below the specified index in
|
|
// our update log.
|
|
if htlc.Index < ourLogIndex {
|
|
ourHTLCs = append(ourHTLCs, htlc)
|
|
}
|
|
}
|
|
|
|
var theirHTLCs []*PaymentDescriptor
|
|
for e := lc.theirUpdateLog.Front(); e != nil; e = e.Next() {
|
|
htlc := e.Value.(*PaymentDescriptor)
|
|
|
|
// If this is an incoming HTLC, then it is only active from
|
|
// this point-of-view if the index of the HTLC addition in
|
|
// their log is below the specified view index.
|
|
if htlc.Index < theirLogIndex {
|
|
theirHTLCs = append(theirHTLCs, htlc)
|
|
}
|
|
}
|
|
|
|
return &htlcView{
|
|
ourUpdates: ourHTLCs,
|
|
theirUpdates: theirHTLCs,
|
|
}
|
|
}
|
|
|
|
// fetchCommitmentView returns a populated commitment which expresses the state
|
|
// of the channel from the point of view of a local or remote chain, evaluating
|
|
// the HTLC log up to the passed indexes. This function is used to construct
|
|
// both local and remote commitment transactions in order to sign or verify new
|
|
// commitment updates. A fully populated commitment is returned which reflects
|
|
// the proper balances for both sides at this point in the commitment chain.
|
|
func (lc *LightningChannel) fetchCommitmentView(remoteChain bool,
|
|
ourLogIndex, theirLogIndex uint32, revocationKey *btcec.PublicKey,
|
|
revocationHash [32]byte) (*commitment, error) {
|
|
|
|
var commitChain *commitmentChain
|
|
if remoteChain {
|
|
commitChain = lc.remoteCommitChain
|
|
} else {
|
|
commitChain = lc.localCommitChain
|
|
}
|
|
|
|
// TODO(roasbeef): don't assume view is always fetched from tip?
|
|
var ourBalance, theirBalance btcutil.Amount
|
|
if commitChain.tip() == nil {
|
|
ourBalance = lc.channelState.OurBalance
|
|
theirBalance = lc.channelState.TheirBalance
|
|
} else {
|
|
ourBalance = commitChain.tip().ourBalance
|
|
theirBalance = commitChain.tip().theirBalance
|
|
}
|
|
|
|
nextHeight := commitChain.tip().height + 1
|
|
|
|
// Run through all the HTLC's that will be covered by this transaction
|
|
// in order to update their commitment addition height, and to adjust
|
|
// the balances on the commitment transaction accordingly.
|
|
// TODO(roasbeef): error if log empty?
|
|
htlcView := lc.fetchHTLCView(theirLogIndex, ourLogIndex)
|
|
filteredHTLCView := lc.evaluateHTLCView(htlcView, &ourBalance, &theirBalance,
|
|
nextHeight, remoteChain)
|
|
|
|
var selfKey *btcec.PublicKey
|
|
var remoteKey *btcec.PublicKey
|
|
var delay uint32
|
|
var delayBalance, p2wkhBalance btcutil.Amount
|
|
if remoteChain {
|
|
selfKey = lc.channelState.TheirCommitKey
|
|
remoteKey = lc.channelState.OurCommitKey
|
|
delay = lc.channelState.RemoteCsvDelay
|
|
delayBalance = theirBalance
|
|
p2wkhBalance = ourBalance
|
|
} else {
|
|
selfKey = lc.channelState.OurCommitKey
|
|
remoteKey = lc.channelState.TheirCommitKey
|
|
delay = lc.channelState.LocalCsvDelay
|
|
delayBalance = ourBalance
|
|
p2wkhBalance = theirBalance
|
|
}
|
|
|
|
// Generate a new commitment transaction with all the latest
|
|
// unsettled/un-timed out HTLC's.
|
|
ourCommitTx := !remoteChain
|
|
commitTx, err := CreateCommitTx(lc.fundingTxIn, selfKey, remoteKey,
|
|
revocationKey, delay, delayBalance, p2wkhBalance)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
for _, htlc := range filteredHTLCView.ourUpdates {
|
|
if err := lc.addHTLC(commitTx, ourCommitTx, htlc,
|
|
revocationHash, delay, false); err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
for _, htlc := range filteredHTLCView.theirUpdates {
|
|
if err := lc.addHTLC(commitTx, ourCommitTx, htlc,
|
|
revocationHash, delay, true); err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
|
|
// Set the state hint of the commitment transaction to facilitate
|
|
// quickly recovering the necessary penalty state in the case of an
|
|
// uncooperative broadcast.
|
|
obsfucator := lc.channelState.StateHintObsfucator
|
|
stateNum := uint32(nextHeight)
|
|
if err := SetStateNumHint(commitTx, stateNum, obsfucator); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Sort the transactions according to the agreed upon cannonical
|
|
// ordering. This lets us skip sending the entire transaction over,
|
|
// instead we'll just send signatures.
|
|
txsort.InPlaceSort(commitTx)
|
|
|
|
return &commitment{
|
|
txn: commitTx,
|
|
height: nextHeight,
|
|
ourBalance: ourBalance,
|
|
ourMessageIndex: ourLogIndex,
|
|
theirMessageIndex: theirLogIndex,
|
|
theirBalance: theirBalance,
|
|
outgoingHTLCs: filteredHTLCView.ourUpdates,
|
|
incomingHTLCs: filteredHTLCView.theirUpdates,
|
|
}, nil
|
|
}
|
|
|
|
// evaluateHTLCView processes all update entries in both HTLC update logs,
|
|
// producing a final view which is the result of properly applying all adds,
|
|
// settles, and timeouts found in both logs. The resulting view returned
|
|
// reflects the current state of htlc's within the remote or local commitment
|
|
// chain.
|
|
func (lc *LightningChannel) evaluateHTLCView(view *htlcView, ourBalance,
|
|
theirBalance *btcutil.Amount, nextHeight uint64, remoteChain bool) *htlcView {
|
|
|
|
newView := &htlcView{}
|
|
|
|
// We use two maps, one for the local log and one for the remote log to
|
|
// keep track of which entries we need to skip when creating the final
|
|
// htlc view. We skip an entry whenever we find a settle or a timeout
|
|
// modifying an entry.
|
|
skipUs := make(map[uint32]struct{})
|
|
skipThem := make(map[uint32]struct{})
|
|
|
|
// First we run through non-add entries in both logs, populating the
|
|
// skip sets and mutating the current chain state (crediting balances, etc) to
|
|
// reflect the settle/timeout entry encountered.
|
|
for _, entry := range view.ourUpdates {
|
|
if entry.EntryType == Add {
|
|
continue
|
|
}
|
|
|
|
addEntry := lc.theirLogIndex[entry.ParentIndex].Value.(*PaymentDescriptor)
|
|
|
|
skipThem[addEntry.Index] = struct{}{}
|
|
processRemoveEntry(entry, ourBalance, theirBalance,
|
|
nextHeight, remoteChain, true)
|
|
}
|
|
for _, entry := range view.theirUpdates {
|
|
if entry.EntryType == Add {
|
|
continue
|
|
}
|
|
|
|
addEntry := lc.ourLogIndex[entry.ParentIndex].Value.(*PaymentDescriptor)
|
|
|
|
skipUs[addEntry.Index] = struct{}{}
|
|
processRemoveEntry(entry, ourBalance, theirBalance,
|
|
nextHeight, remoteChain, false)
|
|
}
|
|
|
|
// Next we take a second pass through all the log entries, skipping any
|
|
// settled HTLC's, and debiting the chain state balance due to any
|
|
// newly added HTLC's.
|
|
for _, entry := range view.ourUpdates {
|
|
isAdd := entry.EntryType == Add
|
|
if _, ok := skipUs[entry.Index]; !isAdd || ok {
|
|
continue
|
|
}
|
|
|
|
processAddEntry(entry, ourBalance, theirBalance, nextHeight,
|
|
remoteChain, false)
|
|
newView.ourUpdates = append(newView.ourUpdates, entry)
|
|
}
|
|
for _, entry := range view.theirUpdates {
|
|
isAdd := entry.EntryType == Add
|
|
if _, ok := skipThem[entry.Index]; !isAdd || ok {
|
|
continue
|
|
}
|
|
|
|
processAddEntry(entry, ourBalance, theirBalance, nextHeight,
|
|
remoteChain, true)
|
|
newView.theirUpdates = append(newView.theirUpdates, entry)
|
|
}
|
|
|
|
return newView
|
|
}
|
|
|
|
// processAddEntry evaluates the effect of an add entry within the HTLC log.
|
|
// If the HTLC hasn't yet been committed in either chain, then the height it
|
|
// was commited is updated. Keeping track of this inclusion height allows us to
|
|
// later compact the log once the change is fully committed in both chains.
|
|
func processAddEntry(htlc *PaymentDescriptor, ourBalance, theirBalance *btcutil.Amount,
|
|
nextHeight uint64, remoteChain bool, isIncoming bool) {
|
|
|
|
// If we're evaluating this entry for the remote chain (to create/view
|
|
// a new commitment), then we'll may be updating the height this entry
|
|
// was added to the chain. Otherwise, we may be updating the entry's
|
|
// height w.r.t the local chain.
|
|
var addHeight *uint64
|
|
if remoteChain {
|
|
addHeight = &htlc.addCommitHeightRemote
|
|
} else {
|
|
addHeight = &htlc.addCommitHeightLocal
|
|
}
|
|
|
|
if *addHeight != 0 {
|
|
return
|
|
}
|
|
|
|
if isIncoming {
|
|
// If this is a new incoming (un-committed) HTLC, then we need
|
|
// to update their balance accordingly by subtracting the
|
|
// amount of the HTLC that are funds pending.
|
|
*theirBalance -= htlc.Amount
|
|
} else {
|
|
// Similarly, we need to debit our balance if this is an out
|
|
// going HTLC to reflect the pending balance.
|
|
*ourBalance -= htlc.Amount
|
|
}
|
|
|
|
*addHeight = nextHeight
|
|
}
|
|
|
|
// processRemoveEntry processes a log entry which settles or timesout a
|
|
// previously added HTLC. If the removal entry has already been processed, it
|
|
// is skipped.
|
|
func processRemoveEntry(htlc *PaymentDescriptor, ourBalance,
|
|
theirBalance *btcutil.Amount, nextHeight uint64,
|
|
remoteChain bool, isIncoming bool) {
|
|
|
|
var removeHeight *uint64
|
|
if remoteChain {
|
|
removeHeight = &htlc.removeCommitHeightRemote
|
|
} else {
|
|
removeHeight = &htlc.removeCommitHeightLocal
|
|
}
|
|
|
|
// Ignore any removal entries which have already been processed.
|
|
if *removeHeight != 0 {
|
|
return
|
|
}
|
|
|
|
switch {
|
|
// If an incoming HTLC is being settled, then this means that we've
|
|
// received the preimage either from another sub-system, or the
|
|
// upstream peer in the route. Therefore, we increase our balance by
|
|
// the HTLC amount.
|
|
case isIncoming && htlc.EntryType == Settle:
|
|
*ourBalance += htlc.Amount
|
|
// Otherwise, this HTLC is being timed out, therefore the value of the
|
|
// HTLC should return to the remote party.
|
|
case isIncoming && htlc.EntryType == Timeout:
|
|
*theirBalance += htlc.Amount
|
|
// If an outgoing HTLC is being settled, then this means that the
|
|
// downstream party resented the preimage or learned of it via a
|
|
// downstream peer. In either case, we credit their settled value with
|
|
// the value of the HTLC.
|
|
case !isIncoming && htlc.EntryType == Settle:
|
|
*theirBalance += htlc.Amount
|
|
// Otherwise, one of our outgoing HTLC's has timed out, so the value of
|
|
// the HTLC should be returned to our settled balance.
|
|
case !isIncoming && htlc.EntryType == Timeout:
|
|
*ourBalance += htlc.Amount
|
|
}
|
|
|
|
*removeHeight = nextHeight
|
|
}
|
|
|
|
// SignNextCommitment signs a new commitment which includes any previous
|
|
// unsettled HTLCs, any new HTLCs, and any modifications to prior HTLCs
|
|
// committed in previous commitment updates. Signing a new commitment
|
|
// decrements the available revocation window by 1. After a successful method
|
|
// call, the remote party's commitment chain is extended by a new commitment
|
|
// which includes all updates to the HTLC log prior to this method invocation.
|
|
func (lc *LightningChannel) SignNextCommitment() ([]byte, uint32, error) {
|
|
// Ensure that we have enough unused revocation hashes given to us by the
|
|
// remote party. If the set is empty, then we're unable to create a new
|
|
// state unless they first revoke a prior commitment transaction.
|
|
if len(lc.revocationWindow) == 0 ||
|
|
len(lc.usedRevocations) == InitialRevocationWindow {
|
|
return nil, 0, ErrNoWindow
|
|
}
|
|
|
|
// Grab the next revocation hash and key to use for this new commitment
|
|
// transaction, if no errors occur then this revocation tuple will be
|
|
// moved to the used set.
|
|
nextRevocation := lc.revocationWindow[0]
|
|
remoteRevocationKey := nextRevocation.NextRevocationKey
|
|
remoteRevocationHash := nextRevocation.NextRevocationHash
|
|
|
|
// Create a new commitment view which will calculate the evaluated
|
|
// state of the remote node's new commitment including our latest added
|
|
// HTLC's. The view includes the latest balances for both sides on the
|
|
// remote node's chain, and also update the addition height of any new
|
|
// HTLC log entries.
|
|
newCommitView, err := lc.fetchCommitmentView(true, lc.ourLogCounter,
|
|
lc.theirLogCounter, remoteRevocationKey, remoteRevocationHash)
|
|
if err != nil {
|
|
return nil, 0, err
|
|
}
|
|
|
|
walletLog.Tracef("ChannelPoint(%v): extending remote chain to height %v",
|
|
lc.channelState.ChanID, newCommitView.height)
|
|
walletLog.Tracef("ChannelPoint(%v): remote chain: our_balance=%v, "+
|
|
"their_balance=%v, commit_tx: %v", lc.channelState.ChanID,
|
|
newCommitView.ourBalance, newCommitView.theirBalance,
|
|
newLogClosure(func() string {
|
|
return spew.Sdump(newCommitView.txn)
|
|
}))
|
|
|
|
// Sign their version of the new commitment transaction.
|
|
lc.signDesc.SigHashes = txscript.NewTxSigHashes(newCommitView.txn)
|
|
sig, err := lc.signer.SignOutputRaw(newCommitView.txn, lc.signDesc)
|
|
if err != nil {
|
|
return nil, 0, err
|
|
}
|
|
|
|
// Extend the remote commitment chain by one with the addition of our
|
|
// latest commitment update.
|
|
lc.remoteCommitChain.addCommitment(newCommitView)
|
|
|
|
// Move the now used revocation hash from the unused set to the used set.
|
|
// We only do this at the end, as we know at this point the procedure will
|
|
// succeed without any errors.
|
|
lc.usedRevocations = append(lc.usedRevocations, nextRevocation)
|
|
lc.revocationWindow[0] = nil // Avoid a GC leak.
|
|
lc.revocationWindow = lc.revocationWindow[1:]
|
|
|
|
// Strip off the sighash flag on the signature in order to send it over
|
|
// the wire.
|
|
return sig, lc.theirLogCounter, nil
|
|
}
|
|
|
|
// ReceiveNewCommitment processs a signature for a new commitment state sent by
|
|
// the remote party. This method will should be called in response to the
|
|
// remote party initiating a new change, or when the remote party sends a
|
|
// signature fully accepting a new state we've initiated. If we are able to
|
|
// succesfully validate the signature, then the generated commitment is added
|
|
// to our local commitment chain. Once we send a revocation for our prior
|
|
// state, then this newly added commitment becomes our current accepted channel
|
|
// state.
|
|
func (lc *LightningChannel) ReceiveNewCommitment(rawSig []byte,
|
|
ourLogIndex uint32) error {
|
|
|
|
theirCommitKey := lc.channelState.TheirCommitKey
|
|
theirMultiSigKey := lc.channelState.TheirMultiSigKey
|
|
|
|
// We're receiving a new commitment which attempts to extend our local
|
|
// commitment chain height by one, so fetch the proper revocation to
|
|
// derive the key+hash needed to construct the new commitment view and
|
|
// state.
|
|
nextHeight := lc.currentHeight + 1
|
|
revocation, err := lc.channelState.LocalElkrem.AtIndex(nextHeight)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
revocationKey := DeriveRevocationPubkey(theirCommitKey, revocation[:])
|
|
revocationHash := fastsha256.Sum256(revocation[:])
|
|
|
|
// With the revocation information calculated, construct the new
|
|
// commitment view which includes all the entries we know of in their
|
|
// HTLC log, and up to ourLogIndex in our HTLC log.
|
|
localCommitmentView, err := lc.fetchCommitmentView(false, ourLogIndex,
|
|
lc.theirLogCounter, revocationKey, revocationHash)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
walletLog.Tracef("ChannelPoint(%v): extending local chain to height %v",
|
|
lc.channelState.ChanID, localCommitmentView.height)
|
|
walletLog.Tracef("ChannelPoint(%v): local chain: our_balance=%v, "+
|
|
"their_balance=%v, commit_tx: %v", lc.channelState.ChanID,
|
|
localCommitmentView.ourBalance, localCommitmentView.theirBalance,
|
|
newLogClosure(func() string {
|
|
return spew.Sdump(localCommitmentView.txn)
|
|
}))
|
|
|
|
// Construct the sighash of the commitment transaction corresponding to
|
|
// this newly proposed state update.
|
|
localCommitTx := localCommitmentView.txn
|
|
multiSigScript := lc.channelState.FundingWitnessScript
|
|
hashCache := txscript.NewTxSigHashes(localCommitTx)
|
|
sigHash, err := txscript.CalcWitnessSigHash(multiSigScript, hashCache,
|
|
txscript.SigHashAll, localCommitTx, 0, int64(lc.channelState.Capacity))
|
|
if err != nil {
|
|
// TODO(roasbeef): fetchview has already mutated the htlc's...
|
|
// * need to either roll-back, or make pure
|
|
return err
|
|
}
|
|
|
|
// Ensure that the newly constructed commitment state has a valid
|
|
// signature.
|
|
sig, err := btcec.ParseSignature(rawSig, btcec.S256())
|
|
if err != nil {
|
|
return err
|
|
} else if !sig.Verify(sigHash, theirMultiSigKey) {
|
|
return fmt.Errorf("invalid commitment signature")
|
|
}
|
|
|
|
// The signature checks out, so we can now add the new commitment to
|
|
// our local commitment chain.
|
|
localCommitmentView.sig = rawSig
|
|
lc.localCommitChain.addCommitment(localCommitmentView)
|
|
|
|
return nil
|
|
}
|
|
|
|
// PendingUpdates returns a boolean value reflecting if there are any pending
|
|
// updates which need to be committed. The state machine has pending updates if
|
|
// the local log index on the local and remote chain tip aren't identical. This
|
|
// indicates that either we have pending updates they need to commit, or vice
|
|
// versa.
|
|
func (lc *LightningChannel) PendingUpdates() bool {
|
|
fullySynced := (lc.localCommitChain.tip().ourMessageIndex ==
|
|
lc.remoteCommitChain.tip().ourMessageIndex)
|
|
|
|
return !fullySynced
|
|
}
|
|
|
|
// RevokeCurrentCommitment revokes the next lowest unrevoked commitment
|
|
// transaction in the local commitment chain. As a result the edge of our
|
|
// revocation window is extended by one, and the tail of our local commitment
|
|
// chain is advanced by a single commitment. This now lowest unrevoked
|
|
// commitment becomes our currently accepted state within the channel.
|
|
func (lc *LightningChannel) RevokeCurrentCommitment() (*lnwire.CommitRevocation, error) {
|
|
theirCommitKey := lc.channelState.TheirCommitKey
|
|
|
|
// Now that we've accept a new state transition, we send the remote
|
|
// party the revocation for our current commitment state.
|
|
revocationMsg := &lnwire.CommitRevocation{}
|
|
currentRevocation, err := lc.channelState.LocalElkrem.AtIndex(lc.currentHeight)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
copy(revocationMsg.Revocation[:], currentRevocation[:])
|
|
|
|
// Along with this revocation, we'll also send an additional extension
|
|
// to our revocation window to the remote party.
|
|
lc.revocationWindowEdge++
|
|
revocationEdge, err := lc.channelState.LocalElkrem.AtIndex(lc.revocationWindowEdge)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
revocationMsg.NextRevocationKey = DeriveRevocationPubkey(theirCommitKey,
|
|
revocationEdge[:])
|
|
revocationMsg.NextRevocationHash = fastsha256.Sum256(revocationEdge[:])
|
|
|
|
walletLog.Tracef("ChannelPoint(%v): revoking height=%v, now at height=%v, window_edge=%v",
|
|
lc.channelState.ChanID, lc.localCommitChain.tail().height,
|
|
lc.currentHeight+1, lc.revocationWindowEdge)
|
|
|
|
// Advance our tail, as we've revoked our previous state.
|
|
lc.localCommitChain.advanceTail()
|
|
lc.currentHeight++
|
|
|
|
// Additionally, generate a channel delta for this state transition for
|
|
// persistent storage.
|
|
// TODO(roasbeef): update sent/received.
|
|
tail := lc.localCommitChain.tail()
|
|
delta, err := tail.toChannelDelta()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
err = lc.channelState.UpdateCommitment(tail.txn, tail.sig, delta)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
walletLog.Tracef("ChannelPoint(%v): state transition accepted: "+
|
|
"our_balance=%v, their_balance=%v", lc.channelState.ChanID,
|
|
tail.ourBalance, tail.theirBalance)
|
|
|
|
revocationMsg.ChannelPoint = lc.channelState.ChanID
|
|
return revocationMsg, nil
|
|
}
|
|
|
|
// ReceiveRevocation processes a revocation sent by the remote party for the
|
|
// lowest unrevoked commitment within their commitment chain. We receive a
|
|
// revocation either during the initial session negotiation wherein revocation
|
|
// windows are extended, or in response to a state update that we initiate. If
|
|
// successful, then the remote commitment chain is advanced by a single
|
|
// commitment, and a log compaction is attempted. In addition, a slice of
|
|
// HTLC's which can be forwarded upstream are returned.
|
|
func (lc *LightningChannel) ReceiveRevocation(revMsg *lnwire.CommitRevocation) ([]*PaymentDescriptor, error) {
|
|
// The revocation has a nil (zero) pre-image, then this should simply be
|
|
// added to the end of the revocation window for the remote node.
|
|
if bytes.Equal(zeroHash[:], revMsg.Revocation[:]) {
|
|
lc.revocationWindow = append(lc.revocationWindow, revMsg)
|
|
return nil, nil
|
|
}
|
|
|
|
ourCommitKey := lc.channelState.OurCommitKey
|
|
currentRevocationKey := lc.channelState.TheirCurrentRevocation
|
|
pendingRevocation := wire.ShaHash(revMsg.Revocation)
|
|
|
|
// Ensure the new pre-image fits in properly within the elkrem receiver
|
|
// tree. If this fails, then all other checks are skipped.
|
|
// TODO(rosbeef): abstract into func
|
|
remoteElkrem := lc.channelState.RemoteElkrem
|
|
if err := remoteElkrem.AddNext(&pendingRevocation); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Verify that the revocation public key we can derive using this
|
|
// pre-image and our private key is identical to the revocation key we
|
|
// were given for their current (prior) commitment transaction.
|
|
revocationPub := DeriveRevocationPubkey(ourCommitKey, pendingRevocation[:])
|
|
if !revocationPub.IsEqual(currentRevocationKey) {
|
|
return nil, fmt.Errorf("revocation key mismatch")
|
|
}
|
|
|
|
// Additionally, we need to ensure we were given the proper pre-image
|
|
// to the revocation hash used within any current HTLC's.
|
|
if !bytes.Equal(lc.channelState.TheirCurrentRevocationHash[:], zeroHash[:]) {
|
|
revokeHash := fastsha256.Sum256(pendingRevocation[:])
|
|
// TODO(roasbeef): rename to drop the "Their"
|
|
if !bytes.Equal(lc.channelState.TheirCurrentRevocationHash[:], revokeHash[:]) {
|
|
return nil, fmt.Errorf("revocation hash mismatch")
|
|
}
|
|
}
|
|
|
|
// Advance the head of the revocation queue now that this revocation has
|
|
// been verified. Additionally, extend the end of our unused revocation
|
|
// queue with the newly extended revocation window update.
|
|
nextRevocation := lc.usedRevocations[0]
|
|
lc.channelState.TheirCurrentRevocation = nextRevocation.NextRevocationKey
|
|
lc.channelState.TheirCurrentRevocationHash = nextRevocation.NextRevocationHash
|
|
lc.usedRevocations[0] = nil // Prevent GC leak.
|
|
lc.usedRevocations = lc.usedRevocations[1:]
|
|
lc.revocationWindow = append(lc.revocationWindow, revMsg)
|
|
|
|
walletLog.Tracef("ChannelPoint(%v): remote party accepted state transition, "+
|
|
"revoked height %v, now at %v", lc.channelState.ChanID,
|
|
lc.remoteCommitChain.tail().height,
|
|
lc.remoteCommitChain.tail().height+1)
|
|
|
|
// At this point, the revocation has been accepted, and we've rotated
|
|
// the current revocation key+hash for the remote party. Therefore we
|
|
// sync now to ensure the elkrem receiver state is consistent with the
|
|
// current commitment height.
|
|
tail := lc.remoteCommitChain.tail()
|
|
delta, err := tail.toChannelDelta()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if err := lc.channelState.AppendToRevocationLog(delta); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Since they revoked the current lowest height in their commitment
|
|
// chain, we can advance their chain by a single commitment.
|
|
lc.remoteCommitChain.advanceTail()
|
|
|
|
remoteChainTail := lc.remoteCommitChain.tail().height
|
|
localChainTail := lc.localCommitChain.tail().height
|
|
|
|
// Now that we've verified the revocation update the state of the HTLC
|
|
// log as we may be able to prune portions of it now, and update their
|
|
// balance.
|
|
var htlcsToForward []*PaymentDescriptor
|
|
for e := lc.theirUpdateLog.Front(); e != nil; e = e.Next() {
|
|
htlc := e.Value.(*PaymentDescriptor)
|
|
|
|
if htlc.isForwarded {
|
|
continue
|
|
}
|
|
|
|
// TODO(roasbeef): re-visit after adding persistence to HTLC's
|
|
// * either record add height, or set to N - 1
|
|
uncomitted := (htlc.addCommitHeightRemote == 0 ||
|
|
htlc.addCommitHeightLocal == 0)
|
|
if htlc.EntryType == Add && uncomitted {
|
|
continue
|
|
}
|
|
|
|
if htlc.EntryType == Add &&
|
|
remoteChainTail >= htlc.addCommitHeightRemote &&
|
|
localChainTail >= htlc.addCommitHeightLocal {
|
|
htlc.isForwarded = true
|
|
htlcsToForward = append(htlcsToForward, htlc)
|
|
} else if htlc.EntryType != Add &&
|
|
remoteChainTail >= htlc.removeCommitHeightRemote &&
|
|
localChainTail >= htlc.removeCommitHeightLocal {
|
|
htlc.isForwarded = true
|
|
htlcsToForward = append(htlcsToForward, htlc)
|
|
}
|
|
}
|
|
|
|
lc.compactLogs(lc.ourUpdateLog, lc.theirUpdateLog,
|
|
localChainTail, remoteChainTail)
|
|
|
|
return htlcsToForward, nil
|
|
}
|
|
|
|
// compactLogs performs garbage collection within the log removing HTLC's which
|
|
// have been removed from the point-of-view of the tail of both chains. The
|
|
// entries which timeout/settle HTLC's are also removed.
|
|
func (lc *LightningChannel) compactLogs(ourLog, theirLog *list.List,
|
|
localChainTail, remoteChainTail uint64) {
|
|
|
|
compactLog := func(logA, logB *list.List, indexB, indexA map[uint32]*list.Element) {
|
|
var nextA *list.Element
|
|
for e := logA.Front(); e != nil; e = nextA {
|
|
nextA = e.Next()
|
|
|
|
htlc := e.Value.(*PaymentDescriptor)
|
|
if htlc.EntryType == Add {
|
|
continue
|
|
}
|
|
|
|
// If the HTLC hasn't yet been removed from either
|
|
// chain, the skip it.
|
|
if htlc.removeCommitHeightRemote == 0 ||
|
|
htlc.removeCommitHeightLocal == 0 {
|
|
continue
|
|
}
|
|
|
|
// Otherwise if the height of the tail of both chains
|
|
// is at least the height in which the HTLC was
|
|
// removed, then evict the settle/timeout entry along
|
|
// with the original add entry.
|
|
if remoteChainTail >= htlc.removeCommitHeightRemote &&
|
|
localChainTail >= htlc.removeCommitHeightLocal {
|
|
parentLink := indexB[htlc.ParentIndex]
|
|
parentIndex := parentLink.Value.(*PaymentDescriptor).Index
|
|
logB.Remove(parentLink)
|
|
|
|
logA.Remove(e)
|
|
|
|
delete(indexB, parentIndex)
|
|
delete(indexA, htlc.Index)
|
|
}
|
|
|
|
}
|
|
}
|
|
|
|
compactLog(ourLog, theirLog, lc.theirLogIndex, lc.ourLogIndex)
|
|
compactLog(theirLog, ourLog, lc.ourLogIndex, lc.theirLogIndex)
|
|
}
|
|
|
|
// ExtendRevocationWindow extends our revocation window by a single revocation,
|
|
// increasing the number of new commitment updates the remote party can
|
|
// initiate without our cooperation.
|
|
func (lc *LightningChannel) ExtendRevocationWindow() (*lnwire.CommitRevocation, error) {
|
|
/// TODO(roasbeef): error if window edge differs from tail by more than
|
|
// InitialRevocationWindow
|
|
|
|
revMsg := &lnwire.CommitRevocation{}
|
|
revMsg.ChannelPoint = lc.channelState.ChanID
|
|
|
|
nextHeight := lc.revocationWindowEdge + 1
|
|
revocation, err := lc.channelState.LocalElkrem.AtIndex(nextHeight)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
theirCommitKey := lc.channelState.TheirCommitKey
|
|
revMsg.NextRevocationKey = DeriveRevocationPubkey(theirCommitKey,
|
|
revocation[:])
|
|
revMsg.NextRevocationHash = fastsha256.Sum256(revocation[:])
|
|
|
|
lc.revocationWindowEdge++
|
|
|
|
return revMsg, nil
|
|
}
|
|
|
|
// AddHTLC adds an HTLC to the state machine's local update log. This method
|
|
// should be called when preparing to send an outgoing HTLC.
|
|
// TODO(roasbeef): check for duplicates below? edge case during restart w/ HTLC
|
|
// persistence
|
|
func (lc *LightningChannel) AddHTLC(htlc *lnwire.HTLCAddRequest) uint32 {
|
|
pd := &PaymentDescriptor{
|
|
EntryType: Add,
|
|
RHash: PaymentHash(htlc.RedemptionHashes[0]),
|
|
Timeout: htlc.Expiry,
|
|
Amount: btcutil.Amount(htlc.Amount),
|
|
Index: lc.ourLogCounter,
|
|
}
|
|
|
|
lc.ourLogIndex[pd.Index] = lc.ourUpdateLog.PushBack(pd)
|
|
lc.ourLogCounter++
|
|
|
|
return pd.Index
|
|
}
|
|
|
|
// ReceiveHTLC adds an HTLC to the state machine's remote update log. This
|
|
// method should be called in response to receiving a new HTLC from the remote
|
|
// party.
|
|
func (lc *LightningChannel) ReceiveHTLC(htlc *lnwire.HTLCAddRequest) uint32 {
|
|
pd := &PaymentDescriptor{
|
|
EntryType: Add,
|
|
RHash: PaymentHash(htlc.RedemptionHashes[0]),
|
|
Timeout: htlc.Expiry,
|
|
Amount: btcutil.Amount(htlc.Amount),
|
|
Index: lc.theirLogCounter,
|
|
}
|
|
|
|
lc.theirLogIndex[pd.Index] = lc.theirUpdateLog.PushBack(pd)
|
|
lc.theirLogCounter++
|
|
|
|
return pd.Index
|
|
}
|
|
|
|
// SettleHTLC attempts to settle an existing outstanding received HTLC. The
|
|
// remote log index of the HTLC settled is returned in order to facilitate
|
|
// creating the corresponding wire message. In the case the supplied pre-image
|
|
// is invalid, an error is returned.
|
|
func (lc *LightningChannel) SettleHTLC(preimage [32]byte) (uint32, error) {
|
|
var targetHTLC *list.Element
|
|
|
|
// TODO(roasbeef): optimize
|
|
paymentHash := fastsha256.Sum256(preimage[:])
|
|
for e := lc.theirUpdateLog.Front(); e != nil; e = e.Next() {
|
|
htlc := e.Value.(*PaymentDescriptor)
|
|
if htlc.EntryType != Add {
|
|
continue
|
|
}
|
|
|
|
if !htlc.settled && bytes.Equal(htlc.RHash[:], paymentHash[:]) {
|
|
htlc.settled = true
|
|
targetHTLC = e
|
|
break
|
|
}
|
|
}
|
|
if targetHTLC == nil {
|
|
return 0, fmt.Errorf("invalid payment hash")
|
|
}
|
|
|
|
parentPd := targetHTLC.Value.(*PaymentDescriptor)
|
|
|
|
pd := &PaymentDescriptor{
|
|
Amount: parentPd.Amount,
|
|
RPreimage: preimage,
|
|
Index: lc.ourLogCounter,
|
|
ParentIndex: parentPd.Index,
|
|
EntryType: Settle,
|
|
}
|
|
|
|
lc.ourUpdateLog.PushBack(pd)
|
|
lc.ourLogCounter++
|
|
|
|
return targetHTLC.Value.(*PaymentDescriptor).Index, nil
|
|
}
|
|
|
|
// ReceiveHTLCSettle attempts to settle an existing outgoing HTLC indexed by an
|
|
// index into the local log. If the specified index doesn't exist within the
|
|
// log, and error is returned. Similarly if the preimage is invalid w.r.t to
|
|
// the referenced of then a distinct error is returned.
|
|
func (lc *LightningChannel) ReceiveHTLCSettle(preimage [32]byte, logIndex uint32) error {
|
|
paymentHash := fastsha256.Sum256(preimage[:])
|
|
addEntry, ok := lc.ourLogIndex[logIndex]
|
|
if !ok {
|
|
return fmt.Errorf("non existant log entry")
|
|
}
|
|
|
|
htlc := addEntry.Value.(*PaymentDescriptor)
|
|
if !bytes.Equal(htlc.RHash[:], paymentHash[:]) {
|
|
return fmt.Errorf("invalid payment hash")
|
|
}
|
|
|
|
pd := &PaymentDescriptor{
|
|
Amount: htlc.Amount,
|
|
RPreimage: preimage,
|
|
ParentIndex: htlc.Index,
|
|
Index: lc.theirLogCounter,
|
|
EntryType: Settle,
|
|
}
|
|
|
|
lc.theirUpdateLog.PushBack(pd)
|
|
lc.theirLogCounter++
|
|
|
|
return nil
|
|
}
|
|
|
|
// TimeoutHTLC...
|
|
func (lc *LightningChannel) TimeoutHTLC() error {
|
|
return nil
|
|
}
|
|
|
|
// ChannelPoint returns the outpoint of the original funding transaction which
|
|
// created this active channel. This outpoint is used throughout various
|
|
// sub-systems to uniquely identify an open channel.
|
|
func (lc *LightningChannel) ChannelPoint() *wire.OutPoint {
|
|
return lc.channelState.ChanID
|
|
}
|
|
|
|
// addHTLC adds a new HTLC to the passed commitment transaction. One of four
|
|
// full scripts will be generated for the HTLC output depending on if the HTLC
|
|
// is incoming and if it's being applied to our commitment transaction or that
|
|
// of the remote node's.
|
|
func (lc *LightningChannel) addHTLC(commitTx *wire.MsgTx, ourCommit bool,
|
|
paymentDesc *PaymentDescriptor, revocation [32]byte, delay uint32,
|
|
isIncoming bool) error {
|
|
|
|
localKey := lc.channelState.OurCommitKey
|
|
remoteKey := lc.channelState.TheirCommitKey
|
|
timeout := paymentDesc.Timeout
|
|
rHash := paymentDesc.RHash
|
|
|
|
// Generate the proper redeem scripts for the HTLC output modified by
|
|
// two-bits denoting if this is an incoming HTLC, and if the HTLC is
|
|
// being applied to their commitment transaction or ours.
|
|
var pkScript []byte
|
|
var err error
|
|
switch {
|
|
// The HTLC is paying to us, and being applied to our commitment
|
|
// transaction. So we need to use the receiver's version of HTLC the
|
|
// script.
|
|
case isIncoming && ourCommit:
|
|
pkScript, err = receiverHTLCScript(timeout, delay, remoteKey,
|
|
localKey, revocation[:], rHash[:])
|
|
// We're being paid via an HTLC by the remote party, and the HTLC is
|
|
// being added to their commitment transaction, so we use the sender's
|
|
// version of the HTLC script.
|
|
case isIncoming && !ourCommit:
|
|
pkScript, err = senderHTLCScript(timeout, delay, remoteKey,
|
|
localKey, revocation[:], rHash[:])
|
|
// We're sending an HTLC which is being added to our commitment
|
|
// transaction. Therefore, we need to use the sender's version of the
|
|
// HTLC script.
|
|
case !isIncoming && ourCommit:
|
|
pkScript, err = senderHTLCScript(timeout, delay, localKey,
|
|
remoteKey, revocation[:], rHash[:])
|
|
// Finally, we're paying the remote party via an HTLC, which is being
|
|
// added to their commitment transaction. Therefore, we use the
|
|
// receiver's version of the HTLC script.
|
|
case !isIncoming && !ourCommit:
|
|
pkScript, err = receiverHTLCScript(timeout, delay, localKey,
|
|
remoteKey, revocation[:], rHash[:])
|
|
}
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// Now that we have the redeem scripts, create the P2WSH public key
|
|
// script for the output itself.
|
|
htlcP2WSH, err := witnessScriptHash(pkScript)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// Add the new HTLC outputs to the respective commitment transactions.
|
|
amountPending := int64(paymentDesc.Amount)
|
|
commitTx.AddTxOut(wire.NewTxOut(amountPending, htlcP2WSH))
|
|
|
|
return nil
|
|
}
|
|
|
|
// ForceCloseSummary describes the final commitment state before the channel is
|
|
// locked-down to initiate a force closure by broadcasting the latest state
|
|
// on-chain. The summary includes all the information required to claim all
|
|
// rightfully owned outputs.
|
|
// TODO(roasbeef): generalize, add HTLC info, revocatio info, etc.
|
|
type ForceCloseSummary struct {
|
|
// CloseTx is the transaction which closed the channel on-chain. If we
|
|
// initiate the force close, then this'll be our latest commitment
|
|
// state. Otherwise, this'll be the state that the remote peer
|
|
// broadcasted on-chain.
|
|
CloseTx *wire.MsgTx
|
|
|
|
// SelfOutpoint is the output created by the above close tx which is
|
|
// spendable by us after a relative time delay.
|
|
SelfOutpoint wire.OutPoint
|
|
|
|
// SelfOutputMaturity is the relative maturity period before the above
|
|
// output can be claimed.
|
|
SelfOutputMaturity uint32
|
|
|
|
// SelfOutputSignDesc is a fully populated sign descriptor capable of
|
|
// generating a valid signature to swee the self output.
|
|
SelfOutputSignDesc *SignDescriptor
|
|
}
|
|
|
|
// ForceClose executes a unilateral closure of the transaction at the current
|
|
// lowest commitment height of the channel. Following a force closure, all
|
|
// state transitions, or modifications to the state update logs will be
|
|
// rejected. Additionally, this function also returns a ForceCloseSummary which
|
|
// includes the necessary details required to sweep all the time-locked within
|
|
// the commitment transaction.
|
|
//
|
|
// TODO(roasbeef): all methods need to abort if in dispute state
|
|
// TODO(roasbeef): method to generate CloseSummaries for when the remote peer
|
|
// does a unilateral close
|
|
func (lc *LightningChannel) ForceClose() (*ForceCloseSummary, error) {
|
|
lc.Lock()
|
|
defer lc.Unlock()
|
|
|
|
// Set the channel state to indicate that the channel is now in a
|
|
// contested state.
|
|
lc.status = channelDispute
|
|
|
|
// Fetch the current commitment transaction, along with their signature
|
|
// for the transaction.
|
|
commitTx := lc.channelState.OurCommitTx
|
|
theirSig := append(lc.channelState.OurCommitSig, byte(txscript.SigHashAll))
|
|
|
|
// With this, we then generate the full witness so the caller can
|
|
// broadcast a fully signed transaction.
|
|
lc.signDesc.SigHashes = txscript.NewTxSigHashes(commitTx)
|
|
ourSigRaw, err := lc.signer.SignOutputRaw(commitTx, lc.signDesc)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
ourSig := append(ourSigRaw, byte(txscript.SigHashAll))
|
|
|
|
// With the final signature generated, create the witness stack
|
|
// required to spend from the multi-sig output.
|
|
ourKey := lc.channelState.OurMultiSigKey.SerializeCompressed()
|
|
theirKey := lc.channelState.TheirMultiSigKey.SerializeCompressed()
|
|
witness := SpendMultiSig(lc.FundingWitnessScript, ourKey, ourSig,
|
|
theirKey, theirSig)
|
|
commitTx.TxIn[0].Witness = witness
|
|
|
|
// Locate the output index of the delayed commitment output back to us.
|
|
// We'll return the details of this output to the caller so they can
|
|
// sweep it once it's mature.
|
|
// TODO(roasbeef): also return HTLC info, assumes only p2wsh is commit
|
|
// tx
|
|
var delayIndex uint32
|
|
var delayScript []byte
|
|
for i, txOut := range commitTx.TxOut {
|
|
if !txscript.IsPayToWitnessScriptHash(txOut.PkScript) {
|
|
continue
|
|
}
|
|
|
|
delayIndex = uint32(i)
|
|
delayScript = txOut.PkScript
|
|
}
|
|
|
|
csvTimeout := lc.channelState.LocalCsvDelay
|
|
selfKey := lc.channelState.OurCommitKey
|
|
|
|
// Re-derive the original pkScript for out to-self output within the
|
|
// commitment transaction. We'll need this for the created sign
|
|
// descriptor.
|
|
elkrem := lc.channelState.LocalElkrem
|
|
unusedRevocation, err := elkrem.AtIndex(lc.currentHeight)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
revokeKey := DeriveRevocationPubkey(lc.channelState.TheirCommitKey,
|
|
unusedRevocation[:])
|
|
selfScript, err := commitScriptToSelf(csvTimeout, selfKey, revokeKey)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// With the necessary information gatehred above, create a new sign
|
|
// descriptor which is capable of generating the signature the caller
|
|
// needs to sweep this output. The hash cache, and input index are not
|
|
// set as the caller will decide these values once sweeping the output.
|
|
selfSignDesc := &SignDescriptor{
|
|
PubKey: selfKey,
|
|
WitnessScript: selfScript,
|
|
Output: &wire.TxOut{
|
|
PkScript: delayScript,
|
|
Value: int64(lc.channelState.OurBalance),
|
|
},
|
|
HashType: txscript.SigHashAll,
|
|
}
|
|
|
|
// Finally, close the channel force close signal which notifies any
|
|
// subscribers that the channel has now been forcibly closed. This
|
|
// allows callers to begin to carry out any post channel closure
|
|
// activities.
|
|
close(lc.ForceCloseSignal)
|
|
|
|
return &ForceCloseSummary{
|
|
CloseTx: commitTx,
|
|
SelfOutpoint: wire.OutPoint{
|
|
Hash: commitTx.TxSha(),
|
|
Index: delayIndex,
|
|
},
|
|
SelfOutputMaturity: csvTimeout,
|
|
SelfOutputSignDesc: selfSignDesc,
|
|
}, nil
|
|
}
|
|
|
|
// InitCooperativeClose initiates a cooperative closure of an active lightning
|
|
// channel. This method should only be executed once all pending HTLCs (if any)
|
|
// on the channel have been cleared/removed. Upon completion, the source channel
|
|
// will shift into the "closing" state, which indicates that all incoming/outgoing
|
|
// HTLC requests should be rejected. A signature for the closing transaction,
|
|
// and the txid of the closing transaction are returned. The initiator of the
|
|
// channel closure should then watch the blockchain for a confirmation of the
|
|
// closing transaction before considering the channel terminated. In the case
|
|
// of an unresponsive remote party, the initiator can either choose to execute
|
|
// a force closure, or backoff for a period of time, and retry the cooperative
|
|
// closure.
|
|
// TODO(roasbeef): caller should initiate signal to reject all incoming HTLCs,
|
|
// settle any inflight.
|
|
func (lc *LightningChannel) InitCooperativeClose() ([]byte, *wire.ShaHash, error) {
|
|
lc.Lock()
|
|
defer lc.Unlock()
|
|
|
|
// If we're already closing the channel, then ignore this request.
|
|
if lc.status == channelClosing || lc.status == channelClosed {
|
|
// TODO(roasbeef): check to ensure no pending payments
|
|
return nil, nil, ErrChanClosing
|
|
}
|
|
|
|
// Otherwise, indicate in the channel status that a channel closure has
|
|
// been initiated.
|
|
lc.status = channelClosing
|
|
|
|
// TODO(roasbeef): assumes initiator pays fees
|
|
closeTx := CreateCooperativeCloseTx(lc.fundingTxIn,
|
|
lc.channelState.OurBalance, lc.channelState.TheirBalance,
|
|
lc.channelState.OurDeliveryScript, lc.channelState.TheirDeliveryScript,
|
|
true)
|
|
closeTxSha := closeTx.TxSha()
|
|
|
|
// Finally, sign the completed cooperative closure transaction. As the
|
|
// initiator we'll simply send our signature over the the remote party,
|
|
// using the generated txid to be notified once the closure transaction
|
|
// has been confirmed.
|
|
lc.signDesc.SigHashes = txscript.NewTxSigHashes(closeTx)
|
|
closeSig, err := lc.signer.SignOutputRaw(closeTx, lc.signDesc)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
return closeSig, &closeTxSha, nil
|
|
}
|
|
|
|
// CompleteCooperativeClose completes the cooperative closure of the target
|
|
// active lightning channel. This method should be called in response to the
|
|
// remote node initating a cooperative channel closure. A fully signed closure
|
|
// transaction is returned. It is the duty of the responding node to broadcast
|
|
// a signed+valid closure transaction to the network.
|
|
//
|
|
// NOTE: The passed remote sig is expected to the a fully complete signature
|
|
// including the proper sighash byte.
|
|
func (lc *LightningChannel) CompleteCooperativeClose(remoteSig []byte) (*wire.MsgTx, error) {
|
|
lc.Lock()
|
|
defer lc.Unlock()
|
|
|
|
// If we're already closing the channel, then ignore this request.
|
|
if lc.status == channelClosing || lc.status == channelClosed {
|
|
// TODO(roasbeef): check to ensure no pending payments
|
|
return nil, ErrChanClosing
|
|
}
|
|
|
|
lc.status = channelClosed
|
|
|
|
// Create the transaction used to return the current settled balance
|
|
// on this active channel back to both parties. In this current model,
|
|
// the initiator pays full fees for the cooperative close transaction.
|
|
closeTx := CreateCooperativeCloseTx(lc.fundingTxIn,
|
|
lc.channelState.OurBalance, lc.channelState.TheirBalance,
|
|
lc.channelState.OurDeliveryScript, lc.channelState.TheirDeliveryScript,
|
|
false)
|
|
|
|
// With the transaction created, we can finally generate our half of
|
|
// the 2-of-2 multi-sig needed to redeem the funding output.
|
|
hashCache := txscript.NewTxSigHashes(closeTx)
|
|
lc.signDesc.SigHashes = hashCache
|
|
closeSig, err := lc.signer.SignOutputRaw(closeTx, lc.signDesc)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Finally, construct the witness stack minding the order of the
|
|
// pubkeys+sigs on the stack.
|
|
ourKey := lc.channelState.OurMultiSigKey.SerializeCompressed()
|
|
theirKey := lc.channelState.TheirMultiSigKey.SerializeCompressed()
|
|
ourSig := append(closeSig, byte(txscript.SigHashAll))
|
|
witness := SpendMultiSig(lc.signDesc.WitnessScript, ourKey, ourSig,
|
|
theirKey, remoteSig)
|
|
closeTx.TxIn[0].Witness = witness
|
|
|
|
// Validate the finalized transaction to ensure the output script is
|
|
// properly met, and that the remote peer supplied a valid signature.
|
|
vm, err := txscript.NewEngine(lc.fundingP2WSH, closeTx, 0,
|
|
txscript.StandardVerifyFlags, nil, hashCache,
|
|
int64(lc.channelState.Capacity))
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if err := vm.Execute(); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return closeTx, nil
|
|
}
|
|
|
|
// DeleteState deletes all state concerning the channel from the underlying
|
|
// database, only leaving a small summary describing meta-data of the
|
|
// channel's lifetime.
|
|
func (lc *LightningChannel) DeleteState() error {
|
|
return lc.channelState.CloseChannel()
|
|
}
|
|
|
|
// StateSnapshot returns a snapshot of the current fully committed state within
|
|
// the channel.
|
|
func (lc *LightningChannel) StateSnapshot() *channeldb.ChannelSnapshot {
|
|
lc.stateMtx.RLock()
|
|
defer lc.stateMtx.RUnlock()
|
|
|
|
return lc.channelState.Snapshot()
|
|
}
|
|
|
|
// CreateCommitTx creates a commitment transaction, spending from specified
|
|
// funding output. The commitment transaction contains two outputs: one paying
|
|
// to the "owner" of the commitment transaction which can be spent after a
|
|
// relative block delay or revocation event, and the other paying the the
|
|
// counter-party within the channel, which can be spent immediately.
|
|
func CreateCommitTx(fundingOutput *wire.TxIn, selfKey, theirKey *btcec.PublicKey,
|
|
revokeKey *btcec.PublicKey, csvTimeout uint32, amountToSelf,
|
|
amountToThem btcutil.Amount) (*wire.MsgTx, error) {
|
|
|
|
// First, we create the script for the delayed "pay-to-self" output.
|
|
// This output has 2 main redemption clauses: either we can redeem the
|
|
// output after a relative block delay, or the remote node can claim
|
|
// the funds with the revocation key if we broadcast a revoked
|
|
// commitment transaction.
|
|
ourRedeemScript, err := commitScriptToSelf(csvTimeout, selfKey,
|
|
revokeKey)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
payToUsScriptHash, err := witnessScriptHash(ourRedeemScript)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Next, we create the script paying to them. This is just a regular
|
|
// P2WKH output, without any added CSV delay.
|
|
theirWitnessKeyHash, err := commitScriptUnencumbered(theirKey)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Now that both output scripts have been created, we can finally create
|
|
// the transaction itself. We use a transaction version of 2 since CSV
|
|
// will fail unless the tx version is >= 2.
|
|
commitTx := wire.NewMsgTx()
|
|
commitTx.Version = 2
|
|
commitTx.AddTxIn(fundingOutput)
|
|
|
|
// Avoid creating zero value outputs within the commitment transaction.
|
|
if amountToSelf != 0 {
|
|
commitTx.AddTxOut(wire.NewTxOut(int64(amountToSelf), payToUsScriptHash))
|
|
}
|
|
if amountToThem != 0 {
|
|
commitTx.AddTxOut(wire.NewTxOut(int64(amountToThem), theirWitnessKeyHash))
|
|
}
|
|
|
|
return commitTx, nil
|
|
}
|
|
|
|
// CreateCooperativeCloseTx creates a transaction which if signed by both
|
|
// parties, then broadcast cooperatively closes an active channel. The creation
|
|
// of the closure transaction is modified by a boolean indicating if the party
|
|
// constructing the channel is the initiator of the closure. Currently it is
|
|
// expected that the initiator pays the transaction fees for the closing
|
|
// transaction in full.
|
|
func CreateCooperativeCloseTx(fundingTxIn *wire.TxIn,
|
|
ourBalance, theirBalance btcutil.Amount,
|
|
ourDeliveryScript, theirDeliveryScript []byte,
|
|
initiator bool) *wire.MsgTx {
|
|
|
|
// Construct the transaction to perform a cooperative closure of the
|
|
// channel. In the event that one side doesn't have any settled funds
|
|
// within the channel then a refund output for that particular side can
|
|
// be omitted.
|
|
closeTx := wire.NewMsgTx()
|
|
closeTx.AddTxIn(fundingTxIn)
|
|
|
|
// The initiator the a cooperative closure pays the fee in entirety.
|
|
// Determine if we're the initiator so we can compute fees properly.
|
|
if initiator {
|
|
// TODO(roasbeef): take sat/byte here instead of properly calc
|
|
ourBalance -= 5000
|
|
} else {
|
|
theirBalance -= 5000
|
|
}
|
|
|
|
// TODO(roasbeef): dust check...
|
|
// * although upper layers should prevent
|
|
if ourBalance != 0 {
|
|
closeTx.AddTxOut(&wire.TxOut{
|
|
PkScript: ourDeliveryScript,
|
|
Value: int64(ourBalance),
|
|
})
|
|
}
|
|
if theirBalance != 0 {
|
|
closeTx.AddTxOut(&wire.TxOut{
|
|
PkScript: theirDeliveryScript,
|
|
Value: int64(theirBalance),
|
|
})
|
|
}
|
|
|
|
txsort.InPlaceSort(closeTx)
|
|
|
|
return closeTx
|
|
}
|