Merge pull request #1287 from projectdiscovery/feature/eviction-strategy

Eviction Strategy

Author: Mzack9999

README.md

@@ -346,6 +346,7 @@ INPUT:
    -lip, -listen-ip string                  public ip address to listen on (default "0.0.0.0")
    -e, -eviction int                        number of days to persist interaction data in memory (default 30)
    -ne, -no-eviction                        disable periodic data eviction from memory
+   -es, -eviction-strategy string           eviction strategy for interactions (sliding, fixed) (default "sliding")
    -a, -auth                                enable authentication to server using random generated token
    -t, -token string                        enable authentication to server using given token
    -acao-url string                         origin url to send in acao header to use web-client) (default "*")

cmd/interactsh-server/main.go

@@ -49,6 +49,7 @@ func main() {
 		flagSet.StringVarP(&cliOptions.ListenIP, "listen-ip", "lip", "0.0.0.0", "public ip address to listen on"),
 		flagSet.IntVarP(&cliOptions.Eviction, "eviction", "e", 30, "number of days to persist interaction data in memory"),
 		flagSet.BoolVarP(&cliOptions.NoEviction, "no-eviction", "ne", false, "disable periodic data eviction from memory"),
+		flagSet.StringVarP(&cliOptions.EvictionStrategy, "eviction-strategy", "es", "sliding", "eviction strategy for interactions (sliding, fixed)"),
 		flagSet.BoolVarP(&cliOptions.Auth, "auth", "a", false, "enable authentication to server using random generated token"),
 		flagSet.StringVarP(&cliOptions.Token, "token", "t", "", "enable authentication to server using given token"),
 		flagSet.StringVar(&cliOptions.OriginURL, "acao-url", "*", "origin url to send in acao header to use web-client)"), // cli flag set to deprecate
@@ -230,9 +231,22 @@ func main() {
 	if cliOptions.NoEviction {
 		evictionTTL = -1
 	}
+
+	// Parse eviction strategy
+	var evictionStrategy storage.EvictionStrategy
+	switch strings.ToLower(cliOptions.EvictionStrategy) {
+	case "fixed":
+		evictionStrategy = storage.EvictionStrategyFixed
+	case "sliding":
+		evictionStrategy = storage.EvictionStrategySliding
+	default:
+		gologger.Fatal().Msgf("invalid eviction strategy '%s', must be 'sliding' or 'fixed'\n", cliOptions.EvictionStrategy)
+	}
+
 	var store storage.Storage
 	storeOptions := storage.DefaultOptions
 	storeOptions.EvictionTTL = evictionTTL
+	storeOptions.EvictionStrategy = evictionStrategy
 	if cliOptions.DiskStorage {
 		if cliOptions.DiskStoragePath == "" {
 			gologger.Fatal().Msgf("disk storage path must be specified\n")

pkg/options/server_options.go

@@ -23,6 +23,7 @@ type CLIServerOptions struct {
 	LdapWithFullLogger       bool
 	Eviction                 int
 	NoEviction               bool
+	EvictionStrategy         string
 	Responder                bool
 	Smb                      bool
 	SmbPort                  int

pkg/storage/option.go

@@ -2,16 +2,25 @@ package storage
 
 import "time"
 
+type EvictionStrategy int
+
+const (
+	EvictionStrategySliding EvictionStrategy = iota // expire-after-access
+	EvictionStrategyFixed                           // expire-after-write
+)
+
 type Options struct {
-	DbPath      string
-	EvictionTTL time.Duration
-	MaxSize     int
+	DbPath           string
+	EvictionTTL      time.Duration
+	MaxSize          int
+	EvictionStrategy EvictionStrategy
 }
 
 func (options *Options) UseDisk() bool {
 	return options.DbPath != ""
 }
 
 var DefaultOptions = Options{
-	MaxSize: 2500000,
+	MaxSize:          2500000,
+	EvictionStrategy: EvictionStrategySliding,
 }

pkg/storage/storagedb.go

@@ -37,7 +37,14 @@ func New(options *Options) (*StorageDB, error) {
 		cache.WithMaximumSize(options.MaxSize),
 	}
 	if options.EvictionTTL > 0 {
-		cacheOptions = append(cacheOptions, cache.WithExpireAfterAccess(options.EvictionTTL))
+		switch options.EvictionStrategy {
+		case EvictionStrategyFixed:
+			cacheOptions = append(cacheOptions, cache.WithExpireAfterWrite(options.EvictionTTL))
+		case EvictionStrategySliding:
+			fallthrough
+		default:
+			cacheOptions = append(cacheOptions, cache.WithExpireAfterAccess(options.EvictionTTL))
+		}
 	}
 	if options.UseDisk() {
 		cacheOptions = append(cacheOptions, cache.WithRemovalListener(storageDB.OnCacheRemovalCallback))

pkg/storage/storagedb_test.go

@@ -133,3 +133,49 @@ func doStuffWithOtherCache(cache cache.Cache) {
 		_, _ = cache.GetIfPresent(strconv.Itoa(i))
 	}
 }
+
+func TestSlidingEvictionStrategy(t *testing.T) {
+	testTTL := 100 * time.Millisecond
+	smallDelay := 10 * time.Millisecond
+	mem, err := New(&Options{EvictionTTL: testTTL, EvictionStrategy: EvictionStrategySliding})
+	require.Nil(t, err)
+	defer mem.Close()
+
+	err = mem.SetID("test-sliding")
+	require.Nil(t, err)
+
+	// Access after half TTL - should extend expiration
+	time.Sleep(testTTL / 2)
+	_, ok := mem.cache.GetIfPresent("test-sliding")
+	require.True(t, ok)
+
+	// Still present after original TTL due to sliding window
+	time.Sleep(testTTL / 2 + smallDelay)
+	_, ok = mem.cache.GetIfPresent("test-sliding")
+	require.True(t, ok)
+
+	// Should be expired after full TTL despite access
+	time.Sleep(testTTL + smallDelay)
+	_, ok = mem.cache.GetIfPresent("test-sliding")
+	require.False(t, ok)
+}
+
+func TestFixedEvictionStrategy(t *testing.T) {
+	testTTL := 100 * time.Millisecond
+	mem, err := New(&Options{EvictionTTL: testTTL, EvictionStrategy: EvictionStrategyFixed})
+	require.Nil(t, err)
+	defer mem.Close()
+
+	err = mem.SetID("test-fixed")
+	require.Nil(t, err)
+
+	// Access after half TTL - should NOT extend expiration
+	time.Sleep(testTTL / 2)
+	_, ok := mem.cache.GetIfPresent("test-fixed")
+	require.True(t, ok)
+
+	// Should be expired after full TTL despite access
+	time.Sleep(testTTL / 2 + 10 * time.Millisecond)
+	_, ok = mem.cache.GetIfPresent("test-fixed")
+	require.False(t, ok)
+}