Add Any helper funcs to the ptypes package.

ptypes/any.go

@@ -0,0 +1,136 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2016 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.
+
+package ptypes
+
+// This file implements functions to marshal proto.Message to/from
+// google.protobuf.Any message.
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/golang/protobuf/ptypes/any"
+)
+
+const googleApis = "type.googleapis.com/"
+
+// AnyMessageName returns the name of the message contained in a google.protobuf.Any message.
+//
+// Note that regular type assertions should be done using the Is
+// function. AnyMessageName is provided for less common use cases like filtering a
+// sequence of Any messages based on a set of allowed message type names.
+func AnyMessageName(any *any.Any) (string, error) {
+	slash := strings.LastIndex(any.TypeUrl, "/")
+	if slash < 0 {
+		return "", fmt.Errorf("message type url %q is invalid", any.TypeUrl)
+	}
+	return any.TypeUrl[slash+1:], nil
+}
+
+// MarshalAny takes the protocol buffer and encodes it into google.protobuf.Any.
+func MarshalAny(pb proto.Message) (*any.Any, error) {
+	value, err := proto.Marshal(pb)
+	if err != nil {
+		return nil, err
+	}
+	return &any.Any{TypeUrl: googleApis + proto.MessageName(pb), Value: value}, nil
+}
+
+// DynamicAny is a value that can be passed to UnmarshalAny to automatically
+// allocate a proto.Message for the type specified in a google.protobuf.Any
+// message. The allocated message is stored in the embedded proto.Message.
+//
+// Example:
+//
+//   var x ptypes.DynamicAny
+//   if err := ptypes.UnmarshalAny(a, &x); err != nil { ... }
+//   fmt.Printf("unmarshaled message: %v", x.Message)
+type DynamicAny struct {
+	proto.Message
+}
+
+// Empty returns a new proto.Message of the type specified in a
+// google.protobuf.Any message. It returns an error if corresponding message
+// type isn't linked in.
+func Empty(any *any.Any) (proto.Message, error) {
+	aname, err := AnyMessageName(any)
+	if err != nil {
+		return nil, err
+	}
+
+	t := proto.MessageType(aname)
+	if t == nil {
+		return nil, fmt.Errorf("any: message type %q isn't linked in", aname)
+	}
+	return reflect.New(t.Elem()).Interface().(proto.Message), nil
+}
+
+// UnmarshalAny parses the protocol buffer representation in a google.protobuf.Any
+// message and places the decoded result in pb. It returns an error if type of
+// contents of Any message does not match type of pb message.
+//
+// pb can be a proto.Message, or a *DynamicAny.
+func UnmarshalAny(any *any.Any, pb proto.Message) error {
+	if d, ok := pb.(*DynamicAny); ok {
+		if d.Message == nil {
+			var err error
+			d.Message, err = Empty(any)
+			if err != nil {
+				return err
+			}
+		}
+		return UnmarshalAny(any, d.Message)
+	}
+
+	aname, err := AnyMessageName(any)
+	if err != nil {
+		return err
+	}
+
+	mname := proto.MessageName(pb)
+	if aname != mname {
+		return fmt.Errorf("mismatched message type: got %q want %q", aname, mname)
+	}
+	return proto.Unmarshal(any.Value, pb)
+}
+
+// Is returns true if any value contains a given message type.
+func Is(any *any.Any, pb proto.Message) bool {
+	aname, err := AnyMessageName(any)
+	if err != nil {
+		return false
+	}
+
+	return aname == proto.MessageName(pb)
+}

ptypes/any_test.go

@@ -0,0 +1,113 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2016 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.
+
+package ptypes
+
+import (
+	"testing"
+
+	"github.com/golang/protobuf/proto"
+	pb "github.com/golang/protobuf/protoc-gen-go/descriptor"
+	"github.com/golang/protobuf/ptypes/any"
+)
+
+func TestMarshalUnmarshal(t *testing.T) {
+	orig := &any.Any{Value: []byte("test")}
+
+	packed, err := MarshalAny(orig)
+	if err != nil {
+		t.Errorf("MarshalAny(%+v): got: _, %v exp: _, nil", orig, err)
+	}
+
+	unpacked := &any.Any{}
+	err = UnmarshalAny(packed, unpacked)
+	if err != nil || !proto.Equal(unpacked, orig) {
+		t.Errorf("got: %v, %+v; want nil, %+v", err, unpacked, orig)
+	}
+}
+
+func TestIs(t *testing.T) {
+	a, err := MarshalAny(&pb.FileDescriptorProto{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if Is(a, &pb.DescriptorProto{}) {
+		t.Error("FileDescriptorProto is not a DescriptorProto, but Is says it is")
+	}
+	if !Is(a, &pb.FileDescriptorProto{}) {
+		t.Error("FileDescriptorProto is indeed a FileDescriptorProto, but Is says it is not")
+	}
+}
+
+func TestIsDifferentUrlPrefixes(t *testing.T) {
+	m := &pb.FileDescriptorProto{}
+	a := &any.Any{TypeUrl: "foo/bar/" + proto.MessageName(m)}
+	if !Is(a, m) {
+		t.Errorf("message with type url %q didn't satisfy Is for type %q", a.TypeUrl, proto.MessageName(m))
+	}
+}
+
+func TestUnmarshalDynamic(t *testing.T) {
+	want := &pb.FileDescriptorProto{Name: proto.String("foo")}
+	a, err := MarshalAny(want)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got DynamicAny
+	if err := UnmarshalAny(a, &got); err != nil {
+		t.Fatal(err)
+	}
+	if !proto.Equal(got.Message, want) {
+		t.Errorf("invalid result from UnmarshalAny, got %q want %q", got.Message, want)
+	}
+}
+
+func TestEmpty(t *testing.T) {
+	want := &pb.FileDescriptorProto{}
+	a, err := MarshalAny(want)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got, err := Empty(a)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !proto.Equal(got, want) {
+		t.Errorf("unequal empty message, got %q, want %q", got, want)
+	}
+
+	// that's a valid type_url for a message which shouldn't be linked into this
+	// test binary. We want an error.
+	a.TypeUrl = "type.googleapis.com/google.protobuf.FieldMask"
+	if _, err := Empty(a); err == nil {
+		t.Errorf("got no error for an attempt to create a message of type %q, which shouldn't be linked in", a.TypeUrl)
+	}
+}