proto, internal/impl: store unknown MessageSet items in non-mset format
In the v1 implementation, unknown MessageSet items are stored in a
message's unknown fields section in non-MessageSet format. For example,
consider a MessageSet containing an item with type_id T and value V.
If the type_id is not resolvable, the item will be placed in the unknown
fields as a bytes-valued field with number T and contents V. This
conversion is then reversed when marshaling a MessageSet containing
unknown fields.
Preserve this behavior in v2.
One consequence of this change is that actual unknown fields in a
MessageSet (any field other than 1) are now discarded. This matches
the previous behavior.
Change-Id: I3d913613f84e0ae82481078dbc91cb25628651cc
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/205697
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
diff --git a/internal/impl/decode.go b/internal/impl/decode.go
index 757bbde..85cc6b0 100644
--- a/internal/impl/decode.go
+++ b/internal/impl/decode.go
@@ -7,6 +7,7 @@
import (
"google.golang.org/protobuf/internal/encoding/wire"
"google.golang.org/protobuf/internal/errors"
+ "google.golang.org/protobuf/internal/flags"
"google.golang.org/protobuf/proto"
pref "google.golang.org/protobuf/reflect/protoreflect"
preg "google.golang.org/protobuf/reflect/protoregistry"
@@ -72,6 +73,9 @@
func (mi *MessageInfo) unmarshalPointer(b []byte, p pointer, groupTag wire.Number, opts unmarshalOptions) (int, error) {
mi.init()
+ if flags.ProtoLegacy && mi.isMessageSet {
+ return unmarshalMessageSet(mi, b, p, opts)
+ }
var exts *map[int32]ExtensionField
start := len(b)
for len(b) > 0 {