Move ReplayLog interface definition to its own file.

Author: Jim Posen

decayedlog.go

@@ -2,7 +2,6 @@ package sphinx
 
 import (
 	"bytes"
-	"crypto/sha256"
 	"encoding/binary"
 	"errors"
 	"fmt"
@@ -20,15 +19,10 @@ const (
 
 	// dbPermissions sets the database permissions to user write-and-readable.
 	dbPermissions = 0600
-
-	// sharedHashSize is the size in bytes of the keys we will be storing
-	// in the DecayedLog. It represents the first 20 bytes of a truncated
-	// sha-256 hash of a secret generated by ECDH.
-	sharedHashSize = 20
 )
 
 var (
-	// sharedHashBucket is a bucket which houses the first sharedHashSize
+	// sharedHashBucket is a bucket which houses the first HashPrefixSize
 	// bytes of a received HTLC's hashed shared secret as the key and the HTLC's
 	// CLTV expiry as the value.
 	sharedHashBucket = []byte("shared-hash")
@@ -39,10 +33,6 @@ var (
 	batchReplayBucket = []byte("batch-replay")
 )
 
-// HashPrefix is a statically size, 20-byte array containing the prefix
-// of a Hash256, and is used to detect duplicate sphinx packets.
-type HashPrefix [sharedHashSize]byte
-
 var (
 	// ErrDecayedLogInit is used to indicate a decayed log failed to create
 	// the proper bucketing structure on startup.
@@ -53,37 +43,8 @@ var (
 	ErrDecayedLogCorrupted = errors.New("decayed log structure corrupted")
 )
 
-// ReplayLog is an interface that defines a new on-disk data structure that
-// contains a persistent log to enable strong replay protection. The interface
-// is general to allow implementations near-complete autonomy. All of these
-// calls should be safe for concurrent access.
-type ReplayLog interface {
-	// Start starts up the on-disk persistent log. It returns an error if
-	// one occurs.
-	Start() error
-
-	// Stop safely stops the on-disk persistent log.
-	Stop() error
-
-	// Get retrieves an entry from the persistent log given its hash prefix. It
-	// returns the value stored and an error if one occurs. Returns
-	// ErrLogEntryNotFound if hash prefix is not in the log.
-	Get(*HashPrefix) (uint32, error)
-
-	// Put stores an entry into the persistent log given a []byte and an
-	// accompanying purposefully general type. It returns an error if the
-	// provided hash prefix already exists in the log.
-	Put(*HashPrefix, uint32) error
-
-	// PutBatch stores
-	PutBatch(*Batch) (*ReplaySet, error)
-
-	// Delete deletes an entry from the persistent log given its hash prefix.
-	Delete(*HashPrefix) error
-}
-
 // DecayedLog implements the PersistLog interface. It stores the first
-// sharedHashSize bytes of a sha256-hashed shared secret along with a node's
+// HashPrefixSize bytes of a sha256-hashed shared secret along with a node's
 // CLTV value. It is a decaying log meaning there will be a garbage collector
 // to collect entries which are expired according to their stored CLTV value
 // and the current block height. DecayedLog wraps boltdb for simplicity and
@@ -282,20 +243,6 @@ func (d *DecayedLog) gcExpiredHashes(height uint32) (uint32, error) {
 	return numExpiredHashes, nil
 }
 
-// hashSharedSecret Sha-256 hashes the shared secret and returns the first
-// sharedHashSize bytes of the hash.
-func hashSharedSecret(sharedSecret *Hash256) HashPrefix {
-	// Sha256 hash of sharedSecret
-	h := sha256.New()
-	h.Write(sharedSecret[:])
-
-	var sharedHash HashPrefix
-
-	// Copy bytes to sharedHash
-	copy(sharedHash[:], h.Sum(nil))
-	return sharedHash
-}
-
 // Delete removes a <shared secret hash, CLTV> key-pair from the
 // sharedHashBucket.
 func (d *DecayedLog) Delete(hash *HashPrefix) error {

decayedlog_test.go

@@ -58,7 +58,7 @@ func (m *mockNotifier) Stop() error {
 func startup(notifier bool) (ReplayLog, *mockNotifier, *HashPrefix, error) {
 	var log ReplayLog
 	var chainNotifier *mockNotifier
-	var hashedSecret HashPrefix
+	var hashedSecret *HashPrefix
 	if notifier {
 
 		// Create the MockNotifier which triggers the garbage collector
@@ -96,7 +96,7 @@ func startup(notifier bool) (ReplayLog, *mockNotifier, *HashPrefix, error) {
 	// This is used as a key to retrieve the cltv value.
 	hashedSecret = hashSharedSecret(&secret)
 
-	return log, chainNotifier, &hashedSecret, nil
+	return log, chainNotifier, hashedSecret, nil
 }
 
 // TestDecayedLogGarbageCollector tests the ability of the garbage collector

replaylog.go

@@ -0,0 +1,60 @@
+package sphinx
+
+import (
+	"crypto/sha256"
+)
+
+const (
+	// HashPrefixSize is the size in bytes of the keys we will be storing
+	// in the DecayedLog. It represents the first 20 bytes of a truncated
+	// sha-256 hash of a secret generated by ECDH.
+	HashPrefixSize = 20
+)
+
+// HashPrefix is a statically size, 20-byte array containing the prefix
+// of a Hash256, and is used to detect duplicate sphinx packets.
+type HashPrefix [HashPrefixSize]byte
+
+// hashSharedSecret Sha-256 hashes the shared secret and returns the first
+// HashPrefixSize bytes of the hash.
+func hashSharedSecret(sharedSecret *Hash256) *HashPrefix {
+	// Sha256 hash of sharedSecret
+	h := sha256.New()
+	h.Write(sharedSecret[:])
+
+	var sharedHash HashPrefix
+
+	// Copy bytes to sharedHash
+	copy(sharedHash[:], h.Sum(nil))
+	return &sharedHash
+}
+
+// ReplayLog is an interface that defines a log of incoming sphinx packets,
+// enabling strong replay protection. The interface is general to allow
+// implementations near-complete autonomy. All methods must be safe for
+// concurrent access.
+type ReplayLog interface {
+	// Start starts up the log. It returns an error if one occurs.
+	Start() error
+
+	// Stop safely stops the log. It returns an error if one occurs.
+	Stop() error
+
+	// Get retrieves an entry from the log given its hash prefix. It returns the
+	// value stored and an error if one occurs. It returns ErrLogEntryNotFound
+	// if the entry is not in the log.
+	Get(*HashPrefix) (uint32, error)
+
+	// Put stores an entry into the log given its hash prefix and an
+	// accompanying purposefully general type. It returns ErrReplayedPacket if
+	// the provided hash prefix already exists in the log.
+	Put(*HashPrefix, uint32) error
+
+	// Delete deletes an entry from the log given its hash prefix.
+	Delete(*HashPrefix) error
+
+	// PutBatch stores a batch of sphinx packets into the log given their hash
+	// prefixes and accompanying values. Returns the set of entries in the batch
+	// that are replays and an error if one occurs.
+	PutBatch(*Batch) (*ReplaySet, error)
+}

sphinx.go

@@ -700,7 +700,7 @@ func (r *Router) ProcessOnionPacket(onionPkt *OnionPacket,
 
 	// Atomically compare this hash prefix with the contents of the on-disk
 	// log, persisting it only if this entry was not detected as a replay.
-	if err := r.log.Put(&hashPrefix, incomingCltv); err != nil {
+	if err := r.log.Put(hashPrefix, incomingCltv); err != nil {
 		return nil, err
 	}
 
@@ -876,7 +876,7 @@ func (t *Tx) ProcessOnionPacket(seqNum uint16, onionPkt *OnionPacket,
 
 	// Add the hash prefix to pending batch of shared secrets that will be
 	// written later via Commit().
-	err = t.batch.Put(seqNum, &hashPrefix, incomingCltv)
+	err = t.batch.Put(seqNum, hashPrefix, incomingCltv)
 	if err != nil {
 		return err
 	}