update config parsing

pkg/registry/resolver.go

@@ -0,0 +1,52 @@
+package registry
+
+import (
+	"context"
+	"net"
+	"sync"
+
+	"github.com/go-gost/gost/pkg/resolver"
+)
+
+var (
+	resolverReg = &resolverRegistry{}
+)
+
+func Resolver() *resolverRegistry {
+	return resolverReg
+}
+
+type resolverRegistry struct {
+	m sync.Map
+}
+
+func (r *resolverRegistry) Register(name string, resolver resolver.Resolver) error {
+	if _, loaded := r.m.LoadOrStore(name, resolver); loaded {
+		return ErrDup
+	}
+
+	return nil
+}
+
+func (r *resolverRegistry) Unregister(name string) {
+	r.m.Delete(name)
+}
+
+func (r *resolverRegistry) Get(name string) resolver.Resolver {
+	if _, ok := r.m.Load(name); !ok {
+		return nil
+	}
+	return &resolverWrapper{name: name}
+}
+
+type resolverWrapper struct {
+	name string
+}
+
+func (w *resolverWrapper) Resolve(ctx context.Context, network, host string) ([]net.IP, error) {
+	r := Resolver().Get(w.name)
+	if r == nil {
+		return nil, ErrNotFound
+	}
+	return r.Resolve(ctx, network, host)
+}