diff --git a/pkg/net/metadata/metadata.go b/pkg/net/metadata/metadata.go
index fb46f3d57..83eb3657c 100644
--- a/pkg/net/metadata/metadata.go
+++ b/pkg/net/metadata/metadata.go
@@ -4,6 +4,8 @@ import (
 	"context"
 	"fmt"
 	"strconv"
+
+	"github.com/pkg/errors"
 )
 
 // MD is a mapping from metadata keys to values.
@@ -132,3 +134,23 @@ func Bool(ctx context.Context, key string) bool {
 		return false
 	}
 }
+
+// Range range value from metadata in context filtered by filterFunc.
+func Range(ctx context.Context, rangeFunc func(key string, value interface{}), filterFunc ...func(key string) bool) {
+	var filter func(key string) bool
+	filterLen := len(filterFunc)
+	if filterLen > 1 {
+		panic(errors.New("metadata: Range got the lenth of filterFunc must less than 2"))
+	} else if filterLen == 1 {
+		filter = filterFunc[0]
+	}
+	md, ok := ctx.Value(mdKey{}).(MD)
+	if !ok {
+		return
+	}
+	for key, value := range md {
+		if filter == nil || filter(key) {
+			rangeFunc(key, value)
+		}
+	}
+}
diff --git a/pkg/net/metadata/metadata_test.go b/pkg/net/metadata/metadata_test.go
index db1e73647..2672da466 100644
--- a/pkg/net/metadata/metadata_test.go
+++ b/pkg/net/metadata/metadata_test.go
@@ -94,3 +94,56 @@ func TestInt64(t *testing.T) {
 	mdcontext = NewContext(context.Background(), MD{Mid: 10})
 	assert.NotEqual(t, int64(10), Int64(mdcontext, Mid))
 }
+
+func TestRange(t *testing.T) {
+	for _, test := range []struct {
+		filterFunc func(key string) bool
+		md         MD
+		want       MD
+	}{
+		{
+			nil,
+			Pairs("foo", "bar"),
+			Pairs("foo", "bar"),
+		},
+		{
+			IsOutgoingKey,
+			Pairs("foo", "bar", RemoteIP, "127.0.0.1", Color, "red", Mirror, "false"),
+			Pairs(RemoteIP, "127.0.0.1", Color, "red", Mirror, "false"),
+		},
+		{
+			IsOutgoingKey,
+			Pairs("foo", "bar", Caller, "app-feed", RemoteIP, "127.0.0.1", Color, "red", Mirror, "true"),
+			Pairs(RemoteIP, "127.0.0.1", Color, "red", Mirror, "true"),
+		},
+		{
+			IsIncomingKey,
+			Pairs("foo", "bar", Caller, "app-feed", RemoteIP, "127.0.0.1", Color, "red", Mirror, "true"),
+			Pairs(Caller, "app-feed", RemoteIP, "127.0.0.1", Color, "red", Mirror, "true"),
+		},
+	} {
+		var mds []MD
+		c := NewContext(context.Background(), test.md)
+		ctx := WithContext(c)
+		Range(ctx,
+			func(key string, value interface{}) {
+				mds = append(mds, Pairs(key, value))
+			},
+			test.filterFunc)
+		rmd := Join(mds...)
+		if !reflect.DeepEqual(rmd, test.want) {
+			t.Fatalf("Range(%v) = %v, want %v", test.md, rmd, test.want)
+		}
+		if test.filterFunc == nil {
+			var mds []MD
+			Range(ctx,
+				func(key string, value interface{}) {
+					mds = append(mds, Pairs(key, value))
+				})
+			rmd := Join(mds...)
+			if !reflect.DeepEqual(rmd, test.want) {
+				t.Fatalf("Range(%v) = %v, want %v", test.md, rmd, test.want)
+			}
+		}
+	}
+}
diff --git a/pkg/net/rpc/warden/client.go b/pkg/net/rpc/warden/client.go
index 1a0ff8752..8f54f02e4 100644
--- a/pkg/net/rpc/warden/client.go
+++ b/pkg/net/rpc/warden/client.go
@@ -83,7 +83,6 @@ func (c *Client) handle() grpc.UnaryClientInterceptor {
 	return func(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) (err error) {
 		var (
 			ok     bool
-			cmd    nmd.MD
 			t      trace.Trace
 			gmd    metadata.MD
 			conf   *ClientConfig
@@ -114,17 +113,13 @@ func (c *Client) handle() grpc.UnaryClientInterceptor {
 		defer onBreaker(brk, &err)
 		_, ctx, cancel = conf.Timeout.Shrink(ctx)
 		defer cancel()
-		if cmd, ok = nmd.FromContext(ctx); ok {
-			for netKey, val := range cmd {
-				if !nmd.IsOutgoingKey(netKey) {
-					continue
+		nmd.Range(ctx,
+			func(key string, value interface{}) {
+				if valstr, ok := value.(string); ok {
+					gmd[key] = []string{valstr}
 				}
-				valstr, ok := val.(string)
-				if ok {
-					gmd[netKey] = []string{valstr}
-				}
-			}
-		}
+			},
+			nmd.IsOutgoingKey)
 		// merge with old matadata if exists
 		if oldmd, ok := metadata.FromOutgoingContext(ctx); ok {
 			gmd = metadata.Join(gmd, oldmd)