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// Go support for Protocol Buffers - Google's data interchange format | ||
// | ||
// Copyright 2017 The Go Authors. All rights reserved. | ||
// https://github.com/golang/protobuf | ||
// | ||
// Redistribution and use in source and binary forms, with or without | ||
// modification, are permitted provided that the following conditions are | ||
// met: | ||
// | ||
// * Redistributions of source code must retain the above copyright | ||
// notice, this list of conditions and the following disclaimer. | ||
// * Redistributions in binary form must reproduce the above | ||
// copyright notice, this list of conditions and the following disclaimer | ||
// in the documentation and/or other materials provided with the | ||
// distribution. | ||
// * Neither the name of Google Inc. nor the names of its | ||
// contributors may be used to endorse or promote products derived from | ||
// this software without specific prior written permission. | ||
// | ||
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | ||
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | ||
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | ||
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | ||
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | ||
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | ||
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | ||
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | ||
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | ||
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | ||
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
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package proto | ||
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import ( | ||
"fmt" | ||
"reflect" | ||
"strings" | ||
) | ||
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// DiscardUnknown recursively discards all unknown fields from this message | ||
// and all embedded messages. | ||
// | ||
// When unmarshaling a message with unrecognized fields, the tags and values | ||
// of such fields are preserved in the Message. This allows a later call to | ||
// marshal to be able to produce a message that continues to have those | ||
// unrecognized fields. To avoid this, DiscardUnknown is used to | ||
// explicitly clear the unknown fields after unmarshaling. | ||
// | ||
// For proto2 messages, the unknown fields of message extensions are only | ||
// discarded from messages that have been accessed via GetExtension. | ||
func DiscardUnknown(m Message) { | ||
discardLegacy(m) | ||
} | ||
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func discardLegacy(m Message) { | ||
v := reflect.ValueOf(m) | ||
if v.Kind() != reflect.Ptr || v.IsNil() { | ||
return | ||
} | ||
v = v.Elem() | ||
if v.Kind() != reflect.Struct { | ||
return | ||
} | ||
t := v.Type() | ||
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for i := 0; i < v.NumField(); i++ { | ||
f := t.Field(i) | ||
if strings.HasPrefix(f.Name, "XXX_") { | ||
continue | ||
} | ||
vf := v.Field(i) | ||
tf := f.Type | ||
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// Unwrap tf to get its most basic type. | ||
var isPointer, isSlice bool | ||
if tf.Kind() == reflect.Slice && tf.Elem().Kind() != reflect.Uint8 { | ||
isSlice = true | ||
tf = tf.Elem() | ||
} | ||
if tf.Kind() == reflect.Ptr { | ||
isPointer = true | ||
tf = tf.Elem() | ||
} | ||
if isPointer && isSlice && tf.Kind() != reflect.Struct { | ||
panic(fmt.Sprintf("%T.%s cannot be a slice of pointers to primitive types", m, f.Name)) | ||
} | ||
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switch tf.Kind() { | ||
case reflect.Struct: | ||
switch { | ||
case !isPointer: | ||
panic(fmt.Sprintf("%T.%s cannot be a direct struct value", m, f.Name)) | ||
case isSlice: // E.g., []*pb.T | ||
for j := 0; j < vf.Len(); j++ { | ||
discardLegacy(vf.Index(j).Interface().(Message)) | ||
} | ||
default: // E.g., *pb.T | ||
discardLegacy(vf.Interface().(Message)) | ||
} | ||
case reflect.Map: | ||
switch { | ||
case isPointer || isSlice: | ||
panic(fmt.Sprintf("%T.%s cannot be a pointer to a map or a slice of map values", m, f.Name)) | ||
default: // E.g., map[K]V | ||
tv := vf.Type().Elem() | ||
if tv.Kind() == reflect.Ptr && tv.Implements(protoMessageType) { // Proto struct (e.g., *T) | ||
for _, key := range vf.MapKeys() { | ||
val := vf.MapIndex(key) | ||
discardLegacy(val.Interface().(Message)) | ||
} | ||
} | ||
} | ||
case reflect.Interface: | ||
// Must be oneof field. | ||
switch { | ||
case isPointer || isSlice: | ||
panic(fmt.Sprintf("%T.%s cannot be a pointer to a interface or a slice of interface values", m, f.Name)) | ||
default: // E.g., test_proto.isCommunique_Union interface | ||
if !vf.IsNil() && f.Tag.Get("protobuf_oneof") != "" { | ||
vf = vf.Elem() // E.g., *test_proto.Communique_Msg | ||
if !vf.IsNil() { | ||
vf = vf.Elem() // E.g., test_proto.Communique_Msg | ||
vf = vf.Field(0) // E.g., Proto struct (e.g., *T) or primitive value | ||
if vf.Kind() == reflect.Ptr { | ||
discardLegacy(vf.Interface().(Message)) | ||
} | ||
} | ||
} | ||
} | ||
} | ||
} | ||
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if vf := v.FieldByName("XXX_unrecognized"); vf.IsValid() { | ||
if vf.Type() != reflect.TypeOf([]byte{}) { | ||
panic("expected XXX_unrecognized to be of type []byte") | ||
} | ||
vf.Set(reflect.ValueOf([]byte(nil))) | ||
} | ||
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// For proto2 messages, only discard unknown fields in message extensions | ||
// that have been accessed via GetExtension. | ||
if em, ok := extendable(m); ok { | ||
// Ignore lock since discardLegacy is not concurrency safe. | ||
emm, _ := em.extensionsRead() | ||
for _, mx := range emm { | ||
if m, ok := mx.value.(Message); ok { | ||
discardLegacy(m) | ||
} | ||
} | ||
} | ||
} |