v1.0.0

common/antireplay/replayfilter.go

@@ -0,0 +1,58 @@
+package antireplay
+
+import (
+	"sync"
+	"time"
+
+	cuckoo "github.com/seiflotfy/cuckoofilter"
+)
+
+const replayFilterCapacity = 100000
+
+// ReplayFilter check for replay attacks.
+type ReplayFilter struct {
+	lock     sync.Mutex
+	poolA    *cuckoo.Filter
+	poolB    *cuckoo.Filter
+	poolSwap bool
+	lastSwap int64
+	interval int64
+}
+
+// NewReplayFilter create a new filter with specifying the expiration time interval in seconds.
+func NewReplayFilter(interval int64) *ReplayFilter {
+	filter := &ReplayFilter{}
+	filter.interval = interval
+	return filter
+}
+
+// Interval in second for expiration time for duplicate records.
+func (filter *ReplayFilter) Interval() int64 {
+	return filter.interval
+}
+
+// Check determine if there are duplicate records.
+func (filter *ReplayFilter) Check(sum []byte) bool {
+	filter.lock.Lock()
+	defer filter.lock.Unlock()
+
+	now := time.Now().Unix()
+	if filter.lastSwap == 0 {
+		filter.lastSwap = now
+		filter.poolA = cuckoo.NewFilter(replayFilterCapacity)
+		filter.poolB = cuckoo.NewFilter(replayFilterCapacity)
+	}
+
+	elapsed := now - filter.lastSwap
+	if elapsed >= filter.Interval() {
+		if filter.poolSwap {
+			filter.poolA.Reset()
+		} else {
+			filter.poolB.Reset()
+		}
+		filter.poolSwap = !filter.poolSwap
+		filter.lastSwap = now
+	}
+
+	return filter.poolA.InsertUnique(sum) && filter.poolB.InsertUnique(sum)
+}