261 lines
7.1 KiB
Go
261 lines
7.1 KiB
Go
package htlcswitch
|
|
|
|
import (
|
|
"bytes"
|
|
"encoding/binary"
|
|
"errors"
|
|
"io"
|
|
"sync"
|
|
|
|
"github.com/lightningnetwork/lnd/channeldb"
|
|
"github.com/lightningnetwork/lnd/channeldb/kvdb"
|
|
"github.com/lightningnetwork/lnd/lnwire"
|
|
"github.com/lightningnetwork/lnd/multimutex"
|
|
)
|
|
|
|
var (
|
|
|
|
// networkResultStoreBucketKey is used for the root level bucket that
|
|
// stores the network result for each payment ID.
|
|
networkResultStoreBucketKey = []byte("network-result-store-bucket")
|
|
|
|
// ErrPaymentIDNotFound is an error returned if the given paymentID is
|
|
// not found.
|
|
ErrPaymentIDNotFound = errors.New("paymentID not found")
|
|
|
|
// ErrPaymentIDAlreadyExists is returned if we try to write a pending
|
|
// payment whose paymentID already exists.
|
|
ErrPaymentIDAlreadyExists = errors.New("paymentID already exists")
|
|
)
|
|
|
|
// PaymentResult wraps a decoded result received from the network after a
|
|
// payment attempt was made. This is what is eventually handed to the router
|
|
// for processing.
|
|
type PaymentResult struct {
|
|
// Preimage is set by the switch in case a sent HTLC was settled.
|
|
Preimage [32]byte
|
|
|
|
// Error is non-nil in case a HTLC send failed, and the HTLC is now
|
|
// irrevocably canceled. If the payment failed during forwarding, this
|
|
// error will be a *ForwardingError.
|
|
Error error
|
|
}
|
|
|
|
// networkResult is the raw result received from the network after a payment
|
|
// attempt has been made. Since the switch doesn't always have the necessary
|
|
// data to decode the raw message, we store it together with some meta data,
|
|
// and decode it when the router query for the final result.
|
|
type networkResult struct {
|
|
// msg is the received result. This should be of type UpdateFulfillHTLC
|
|
// or UpdateFailHTLC.
|
|
msg lnwire.Message
|
|
|
|
// unencrypted indicates whether the failure encoded in the message is
|
|
// unencrypted, and hence doesn't need to be decrypted.
|
|
unencrypted bool
|
|
|
|
// isResolution indicates whether this is a resolution message, in
|
|
// which the failure reason might not be included.
|
|
isResolution bool
|
|
}
|
|
|
|
// serializeNetworkResult serializes the networkResult.
|
|
func serializeNetworkResult(w io.Writer, n *networkResult) error {
|
|
if _, err := lnwire.WriteMessage(w, n.msg, 0); err != nil {
|
|
return err
|
|
}
|
|
|
|
return channeldb.WriteElements(w, n.unencrypted, n.isResolution)
|
|
}
|
|
|
|
// deserializeNetworkResult deserializes the networkResult.
|
|
func deserializeNetworkResult(r io.Reader) (*networkResult, error) {
|
|
var (
|
|
err error
|
|
)
|
|
|
|
n := &networkResult{}
|
|
|
|
n.msg, err = lnwire.ReadMessage(r, 0)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
if err := channeldb.ReadElements(r,
|
|
&n.unencrypted, &n.isResolution,
|
|
); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return n, nil
|
|
}
|
|
|
|
// networkResultStore is a persistent store that stores any results of HTLCs in
|
|
// flight on the network. Since payment results are inherently asynchronous, it
|
|
// is used as a common access point for senders of HTLCs, to know when a result
|
|
// is back. The Switch will checkpoint any received result to the store, and
|
|
// the store will keep results and notify the callers about them.
|
|
type networkResultStore struct {
|
|
db *channeldb.DB
|
|
|
|
// results is a map from paymentIDs to channels where subscribers to
|
|
// payment results will be notified.
|
|
results map[uint64][]chan *networkResult
|
|
resultsMtx sync.Mutex
|
|
|
|
// paymentIDMtx is a multimutex used to make sure the database and
|
|
// result subscribers map is consistent for each payment ID in case of
|
|
// concurrent callers.
|
|
paymentIDMtx *multimutex.Mutex
|
|
}
|
|
|
|
func newNetworkResultStore(db *channeldb.DB) *networkResultStore {
|
|
return &networkResultStore{
|
|
db: db,
|
|
results: make(map[uint64][]chan *networkResult),
|
|
paymentIDMtx: multimutex.NewMutex(),
|
|
}
|
|
}
|
|
|
|
// storeResult stores the networkResult for the given paymentID, and
|
|
// notifies any subscribers.
|
|
func (store *networkResultStore) storeResult(paymentID uint64,
|
|
result *networkResult) error {
|
|
|
|
// We get a mutex for this payment ID. This is needed to ensure
|
|
// consistency between the database state and the subscribers in case
|
|
// of concurrent calls.
|
|
store.paymentIDMtx.Lock(paymentID)
|
|
defer store.paymentIDMtx.Unlock(paymentID)
|
|
|
|
// Serialize the payment result.
|
|
var b bytes.Buffer
|
|
if err := serializeNetworkResult(&b, result); err != nil {
|
|
return err
|
|
}
|
|
|
|
var paymentIDBytes [8]byte
|
|
binary.BigEndian.PutUint64(paymentIDBytes[:], paymentID)
|
|
|
|
err := kvdb.Batch(store.db.Backend, func(tx kvdb.RwTx) error {
|
|
networkResults, err := tx.CreateTopLevelBucket(
|
|
networkResultStoreBucketKey,
|
|
)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
return networkResults.Put(paymentIDBytes[:], b.Bytes())
|
|
})
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// Now that the result is stored in the database, we can notify any
|
|
// active subscribers.
|
|
store.resultsMtx.Lock()
|
|
for _, res := range store.results[paymentID] {
|
|
res <- result
|
|
}
|
|
delete(store.results, paymentID)
|
|
store.resultsMtx.Unlock()
|
|
|
|
return nil
|
|
}
|
|
|
|
// subscribeResult is used to get the payment result for the given
|
|
// payment ID. It returns a channel on which the result will be delivered when
|
|
// ready.
|
|
func (store *networkResultStore) subscribeResult(paymentID uint64) (
|
|
<-chan *networkResult, error) {
|
|
|
|
// We get a mutex for this payment ID. This is needed to ensure
|
|
// consistency between the database state and the subscribers in case
|
|
// of concurrent calls.
|
|
store.paymentIDMtx.Lock(paymentID)
|
|
defer store.paymentIDMtx.Unlock(paymentID)
|
|
|
|
var (
|
|
result *networkResult
|
|
resultChan = make(chan *networkResult, 1)
|
|
)
|
|
|
|
err := kvdb.View(store.db, func(tx kvdb.ReadTx) error {
|
|
var err error
|
|
result, err = fetchResult(tx, paymentID)
|
|
switch {
|
|
|
|
// Result not yet available, we will notify once a result is
|
|
// available.
|
|
case err == ErrPaymentIDNotFound:
|
|
return nil
|
|
|
|
case err != nil:
|
|
return err
|
|
|
|
// The result was found, and will be returned immediately.
|
|
default:
|
|
return nil
|
|
}
|
|
})
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// If the result was found, we can send it on the result channel
|
|
// imemdiately.
|
|
if result != nil {
|
|
resultChan <- result
|
|
return resultChan, nil
|
|
}
|
|
|
|
// Otherwise we store the result channel for when the result is
|
|
// available.
|
|
store.resultsMtx.Lock()
|
|
store.results[paymentID] = append(
|
|
store.results[paymentID], resultChan,
|
|
)
|
|
store.resultsMtx.Unlock()
|
|
|
|
return resultChan, nil
|
|
}
|
|
|
|
// getResult attempts to immediately fetch the result for the given pid from
|
|
// the store. If no result is available, ErrPaymentIDNotFound is returned.
|
|
func (store *networkResultStore) getResult(pid uint64) (
|
|
*networkResult, error) {
|
|
|
|
var result *networkResult
|
|
err := kvdb.View(store.db, func(tx kvdb.ReadTx) error {
|
|
var err error
|
|
result, err = fetchResult(tx, pid)
|
|
return err
|
|
})
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return result, nil
|
|
}
|
|
|
|
func fetchResult(tx kvdb.ReadTx, pid uint64) (*networkResult, error) {
|
|
var paymentIDBytes [8]byte
|
|
binary.BigEndian.PutUint64(paymentIDBytes[:], pid)
|
|
|
|
networkResults := tx.ReadBucket(networkResultStoreBucketKey)
|
|
if networkResults == nil {
|
|
return nil, ErrPaymentIDNotFound
|
|
}
|
|
|
|
// Check whether a result is already available.
|
|
resultBytes := networkResults.Get(paymentIDBytes[:])
|
|
if resultBytes == nil {
|
|
return nil, ErrPaymentIDNotFound
|
|
}
|
|
|
|
// Decode the result we found.
|
|
r := bytes.NewReader(resultBytes)
|
|
|
|
return deserializeNetworkResult(r)
|
|
}
|