chore(pkg/middlewares): use settings for cache and filter constructor…

…s (future proofing for compatibility)

pkg/middlewares/cache/middleware.go

@@ -1,6 +1,8 @@
 package cache
 
 import (
+	"fmt"
+
 	"github.com/miekg/dns"
 	"github.com/qdm12/dns/v2/internal/stateful"
 )
@@ -9,10 +11,15 @@ type Middleware struct {
 	cache Cache
 }
 
-func New(cache Cache) *Middleware {
-	return &Middleware{
-		cache: cache,
+func New(settings Settings) (middleware *Middleware, err error) {
+	err = settings.Validate()
+	if err != nil {
+		return nil, fmt.Errorf("settings validation: %w", err)
 	}
+
+	return &Middleware{
+		cache: settings.Cache,
+	}, nil
 }
 
 func (m *Middleware) Wrap(next dns.Handler) dns.Handler { //nolint:ireturn

pkg/middlewares/cache/settings.go

@@ -0,0 +1,22 @@
+package cache
+
+import (
+	"errors"
+	"fmt"
+)
+
+type Settings struct {
+	Cache Cache
+}
+
+var (
+	ErrCacheMustBeSet = errors.New("cache must be set")
+)
+
+func (s *Settings) Validate() (err error) {
+	if s.Cache == nil {
+		return fmt.Errorf("%w", ErrCacheMustBeSet)
+	}
+
+	return nil
+}

pkg/middlewares/filter/middleware.go

@@ -1,6 +1,8 @@
 package filter
 
 import (
+	"fmt"
+
 	"github.com/miekg/dns"
 	"github.com/qdm12/dns/v2/internal/stateful"
 )
@@ -9,10 +11,15 @@ type Middleware struct {
 	filter Filter
 }
 
-func New(filter Filter) *Middleware {
-	return &Middleware{
-		filter: filter,
+func New(settings Settings) (middleware *Middleware, err error) {
+	err = settings.Validate()
+	if err != nil {
+		return nil, fmt.Errorf("settings validation: %w", err)
 	}
+
+	return &Middleware{
+		filter: settings.Filter,
+	}, nil
 }
 
 func (m *Middleware) Wrap(next dns.Handler) dns.Handler { //nolint:ireturn

pkg/middlewares/filter/settings.go

@@ -0,0 +1,22 @@
+package filter
+
+import (
+	"errors"
+	"fmt"
+)
+
+type Settings struct {
+	Filter Filter
+}
+
+var (
+	ErrFilterMustBeSet = errors.New("filter must be set")
+)
+
+func (s *Settings) Validate() (err error) {
+	if s.Filter == nil {
+		return fmt.Errorf("%w", ErrFilterMustBeSet)
+	}
+
+	return nil
+}