106 lines
3.5 KiB
Go
106 lines
3.5 KiB
Go
package wtdb
|
|
|
|
import (
|
|
"errors"
|
|
|
|
"github.com/lightningnetwork/lnd/lnwallet"
|
|
)
|
|
|
|
var (
|
|
// ErrSessionNotFound is returned when querying by session id for a
|
|
// session that does not exist.
|
|
ErrSessionNotFound = errors.New("session not found in db")
|
|
|
|
// ErrSessionAlreadyExists signals that a session creation failed
|
|
// because a session with the same session id already exists.
|
|
ErrSessionAlreadyExists = errors.New("session already exists")
|
|
|
|
// ErrUpdateOutOfOrder is returned when the sequence number is not equal
|
|
// to the server's LastApplied+1.
|
|
ErrUpdateOutOfOrder = errors.New("update sequence number is not " +
|
|
"sequential")
|
|
|
|
// ErrLastAppliedReversion is returned when the client echos a
|
|
// last-applied value that is less than it claimed in a prior update.
|
|
ErrLastAppliedReversion = errors.New("update last applied must be " +
|
|
"non-decreasing")
|
|
|
|
// ErrSeqNumAlreadyApplied is returned when the client sends a sequence
|
|
// number for which they already claim to have an ACK.
|
|
ErrSeqNumAlreadyApplied = errors.New("update sequence number has " +
|
|
"already been applied")
|
|
|
|
// ErrSessionConsumed is returned if the client tries to send a sequence
|
|
// number larger than the session's max number of updates.
|
|
ErrSessionConsumed = errors.New("all session updates have been " +
|
|
"consumed")
|
|
)
|
|
|
|
// SessionInfo holds the negotiated session parameters for single session id,
|
|
// and handles the acceptance and validation of state updates sent by the
|
|
// client.
|
|
type SessionInfo struct {
|
|
// ID is the remote public key of the watchtower client.
|
|
ID SessionID
|
|
|
|
// Version specifies the plaintext blob encoding of all state updates.
|
|
Version uint16
|
|
|
|
// MaxUpdates is the total number of updates the client can send for
|
|
// this session.
|
|
MaxUpdates uint16
|
|
|
|
// LastApplied the sequence number of the last successful state update.
|
|
LastApplied uint16
|
|
|
|
// ClientLastApplied the last last-applied the client has echoed back.
|
|
ClientLastApplied uint16
|
|
|
|
// RewardRate the fraction of the swept amount that goes to the tower,
|
|
// expressed in millionths of the swept balance.
|
|
RewardRate uint32
|
|
|
|
// SweepFeeRate is the agreed upon fee rate used to sign any sweep
|
|
// transactions.
|
|
SweepFeeRate lnwallet.SatPerKWeight
|
|
|
|
// RewardAddress the address that the tower's reward will be deposited
|
|
// to if a sweep transaction confirms.
|
|
RewardAddress []byte
|
|
|
|
// TODO(conner): store client metrics, DOS score, etc
|
|
}
|
|
|
|
// AcceptUpdateSequence validates that a state update's sequence number and last
|
|
// applied are valid given our past history with the client. These checks ensure
|
|
// that clients are properly in sync and following the update protocol properly.
|
|
// If validation is successful, the receiver's LastApplied and ClientLastApplied
|
|
// are updated with the latest values presented by the client. Any errors
|
|
// returned from this method are converted into an appropriate
|
|
// wtwire.StateUpdateCode.
|
|
func (s *SessionInfo) AcceptUpdateSequence(seqNum, lastApplied uint16) error {
|
|
switch {
|
|
|
|
// Client already claims to have an ACK for this seqnum.
|
|
case seqNum <= lastApplied:
|
|
return ErrSeqNumAlreadyApplied
|
|
|
|
// Client echos a last applied that is lower than previously sent.
|
|
case lastApplied < s.ClientLastApplied:
|
|
return ErrLastAppliedReversion
|
|
|
|
// Client update exceeds capacity of session.
|
|
case seqNum > s.MaxUpdates:
|
|
return ErrSessionConsumed
|
|
|
|
// Client update does not match our expected next seqnum.
|
|
case seqNum != s.LastApplied+1:
|
|
return ErrUpdateOutOfOrder
|
|
}
|
|
|
|
s.LastApplied = seqNum
|
|
s.ClientLastApplied = lastApplied
|
|
|
|
return nil
|
|
}
|