feat: add WAFWithRules interface with RulesCount() (#1492)

Add WAFWithRules interface with RulesCount()

Author: ppomes

experimental/waf.go

@@ -15,3 +15,11 @@ type Options = corazawaf.Options
 type WAFWithOptions interface {
 	NewTransactionWithOptions(Options) types.Transaction
 }
+
+// WAFWithRules is an interface that allows to inspect the number of
+// rules loaded in a WAF instance. This is useful for connectors that
+// need to verify rule loading or implement configuration caching.
+type WAFWithRules interface {
+	// RulesCount returns the number of rules in this WAF.
+	RulesCount() int
+}

waf.go

@@ -154,3 +154,8 @@ func (w wafWrapper) NewTransactionWithID(id string) types.Transaction {
 func (w wafWrapper) NewTransactionWithOptions(opts corazawaf.Options) types.Transaction {
 	return w.waf.NewTransactionWithOptions(opts)
 }
+
+// RulesCount returns the number of rules in this WAF.
+func (w wafWrapper) RulesCount() int {
+	return w.waf.Rules.Count()
+}

waf_test.go

@@ -13,6 +13,11 @@ import (
 	"github.com/corazawaf/coraza/v3/types"
 )
 
+// wafWithRules mirrors experimental.WAFWithRules for testing without import cycle.
+type wafWithRules interface {
+	RulesCount() int
+}
+
 func TestRequestBodyLimit(t *testing.T) {
 	testCases := map[string]struct {
 		expectedErr   error
@@ -178,3 +183,33 @@ func TestPopulateAuditLog(t *testing.T) {
 		})
 	}
 }
+
+func TestRulesCount(t *testing.T) {
+	waf, err := NewWAF(NewWAFConfig())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rules, ok := waf.(wafWithRules)
+	if !ok {
+		t.Fatal("WAF does not implement WAFWithRules")
+	}
+	if rules.RulesCount() != 0 {
+		t.Fatalf("expected 0 rules, got %d", rules.RulesCount())
+	}
+
+	waf, err = NewWAF(NewWAFConfig().
+		WithDirectives(`SecRule REMOTE_ADDR "127.0.0.1" "id:1,phase:1,deny,status:403"`).
+		WithDirectives(`SecRule REQUEST_URI "/test" "id:2,phase:1,deny,status:403"`))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rules, ok = waf.(wafWithRules)
+	if !ok {
+		t.Fatal("WAF does not implement WAFWithRules")
+	}
+	if rules.RulesCount() != 2 {
+		t.Fatalf("expected 2 rules, got %d", rules.RulesCount())
+	}
+}