Add Fake DNS support (#309)

Co-authored-by: Xiaokang Wang <xiaokangwang@outlook.com>
Co-authored-by: loyalsoldier <10487845+Loyalsoldier@users.noreply.github.com>
Co-authored-by: kslr <kslrwang@gmail.com>

common/cache/lru_test.go

@@ -0,0 +1,86 @@
+package cache_test
+
+import (
+	"testing"
+
+	. "github.com/xtls/xray-core/common/cache"
+)
+
+func TestLruReplaceValue(t *testing.T) {
+	lru := NewLru(2)
+	lru.Put(2, 6)
+	lru.Put(1, 5)
+	lru.Put(1, 2)
+	v, _ := lru.Get(1)
+	if v != 2 {
+		t.Error("should get 2", v)
+	}
+	v, _ = lru.Get(2)
+	if v != 6 {
+		t.Error("should get 6", v)
+	}
+}
+
+func TestLruRemoveOld(t *testing.T) {
+	lru := NewLru(2)
+	v, ok := lru.Get(2)
+	if ok {
+		t.Error("should get nil", v)
+	}
+	lru.Put(1, 1)
+	lru.Put(2, 2)
+	v, _ = lru.Get(1)
+	if v != 1 {
+		t.Error("should get 1", v)
+	}
+	lru.Put(3, 3)
+	v, ok = lru.Get(2)
+	if ok {
+		t.Error("should get nil", v)
+	}
+	lru.Put(4, 4)
+	v, ok = lru.Get(1)
+	if ok {
+		t.Error("should get nil", v)
+	}
+	v, _ = lru.Get(3)
+	if v != 3 {
+		t.Error("should get 3", v)
+	}
+	v, _ = lru.Get(4)
+	if v != 4 {
+		t.Error("should get 4", v)
+	}
+}
+
+func TestGetKeyFromValue(t *testing.T) {
+	lru := NewLru(2)
+	lru.Put(3, 3)
+	lru.Put(2, 2)
+	lru.GetKeyFromValue(3)
+	lru.Put(1, 1)
+	v, ok := lru.GetKeyFromValue(2)
+	if ok {
+		t.Error("should get nil", v)
+	}
+	v, _ = lru.GetKeyFromValue(3)
+	if v != 3 {
+		t.Error("should get 3", v)
+	}
+}
+
+func TestPeekKeyFromValue(t *testing.T) {
+	lru := NewLru(2)
+	lru.Put(3, 3)
+	lru.Put(2, 2)
+	lru.PeekKeyFromValue(3)
+	lru.Put(1, 1)
+	v, ok := lru.PeekKeyFromValue(3)
+	if ok {
+		t.Error("should get nil", v)
+	}
+	v, _ = lru.PeekKeyFromValue(2)
+	if v != 2 {
+		t.Error("should get 2", v)
+	}
+}