1 // Copyright 2019 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4 5 package proto
6 7 import (
8 "google.golang.org/protobuf/reflect/protoreflect"
9 )
10 11 // DiscardUnknown recursively discards all unknown fields from this message
12 // and all embedded messages.
13 //
14 // When unmarshaling a message with unrecognized fields, the tags and values
15 // of such fields are preserved in the Message. This allows a later call to
16 // marshal to be able to produce a message that continues to have those
17 // unrecognized fields. To avoid this, DiscardUnknown is used to
18 // explicitly clear the unknown fields after unmarshaling.
19 func DiscardUnknown(m Message) {
20 if m != nil {
21 discardUnknown(MessageReflect(m))
22 }
23 }
24 25 func discardUnknown(m protoreflect.Message) {
26 m.Range(func(fd protoreflect.FieldDescriptor, val protoreflect.Value) bool {
27 switch {
28 // Handle singular message.
29 case fd.Cardinality() != protoreflect.Repeated:
30 if fd.Message() != nil {
31 discardUnknown(m.Get(fd).Message())
32 }
33 // Handle list of messages.
34 case fd.IsList():
35 if fd.Message() != nil {
36 ls := m.Get(fd).List()
37 for i := 0; i < ls.Len(); i++ {
38 discardUnknown(ls.Get(i).Message())
39 }
40 }
41 // Handle map of messages.
42 case fd.IsMap():
43 if fd.MapValue().Message() != nil {
44 ms := m.Get(fd).Map()
45 ms.Range(func(_ protoreflect.MapKey, v protoreflect.Value) bool {
46 discardUnknown(v.Message())
47 return true
48 })
49 }
50 }
51 return true
52 })
53 54 // Discard unknown fields.
55 if len(m.GetUnknown()) > 0 {
56 m.SetUnknown(nil)
57 }
58 }
59