Merge pull request #129 from 9seconds/disable-antireplay

Possibility to disable antireplay cache

README.md

 (probability is 1/(2^64)) but it could be quite effective to prevent
 replays.
 
+It is possible to disable this cache. To do that, please explicitly set
+its size to 0.
+
 
 ## FakeTLS
 

antireplay/cache.go

 	data *fastcache.Cache
 }
 
-func (c *cache) AddObfuscated2(data []byte) {
+func (c cache) AddObfuscated2(data []byte) {
 	c.data.Set(keyObfuscated2(data), nil)
 }
 
-func (c *cache) AddTLS(data []byte) {
+func (c cache) AddTLS(data []byte) {
 	c.data.Set(keyTLS(data), nil)
 }
 
-func (c *cache) HasObfuscated2(data []byte) bool {
+func (c cache) HasObfuscated2(data []byte) bool {
 	return c.data.Has(keyObfuscated2(data))
 }
 
-func (c *cache) HasTLS(data []byte) bool {
+func (c cache) HasTLS(data []byte) bool {
 	return c.data.Has(keyTLS(data))
 }
 

antireplay/init.go

 	"github.com/9seconds/mtg/config"
 )
 
+type CacheInterface interface {
+	AddObfuscated2([]byte)
+	AddTLS([]byte)
+	HasObfuscated2([]byte) bool
+	HasTLS([]byte) bool
+}
+
 var (
-	Cache    cache
+	Cache    CacheInterface
 	initOnce sync.Once
 )
 
 func Init() {
 	initOnce.Do(func() {
-		Cache.data = fastcache.New(config.C.AntiReplayMaxSize)
+		if config.C.AntiReplayMaxSize == 0 {
+			Cache = nilCache{}
+		} else {
+			Cache = cache{fastcache.New(config.C.AntiReplayMaxSize)}
+		}
 	})
 }

antireplay/nilcache.go

+package antireplay
+
+type nilCache struct{}
+
+func (n nilCache) AddObfuscated2(_ []byte)      {}
+func (n nilCache) AddTLS(_ []byte)              {}
+func (n nilCache) HasObfuscated2(_ []byte) bool { return false }
+func (n nilCache) HasTLS(_ []byte) bool         { return false }