1 // Go support for Protocol Buffers - Google's data interchange format 2 // 3 // Copyright 2016 The Go Authors. All rights reserved. 4 // https://github.com/golang/protobuf 5 // 6 // Redistribution and use in source and binary forms, with or without 7 // modification, are permitted provided that the following conditions are 8 // met: 9 // 10 // * Redistributions of source code must retain the above copyright 11 // notice, this list of conditions and the following disclaimer. 12 // * Redistributions in binary form must reproduce the above 13 // copyright notice, this list of conditions and the following disclaimer 14 // in the documentation and/or other materials provided with the 15 // distribution. 16 // * Neither the name of Google Inc. nor the names of its 17 // contributors may be used to endorse or promote products derived from 18 // this software without specific prior written permission. 19 // 20 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 23 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 24 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 25 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 26 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 30 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 32 package types 33 34 // This file implements functions to marshal proto.Message to/from 35 // google.protobuf.Any message. 36 37 import ( 38 "fmt" 39 "reflect" 40 "strings" 41 42 "github.com/gogo/protobuf/proto" 43 ) 44 45 const googleApis = "type.googleapis.com/" 46 47 // AnyMessageName returns the name of the message contained in a google.protobuf.Any message. 48 // 49 // Note that regular type assertions should be done using the Is 50 // function. AnyMessageName is provided for less common use cases like filtering a 51 // sequence of Any messages based on a set of allowed message type names. 52 func AnyMessageName(any *Any) (string, error) { 53 if any == nil { 54 return "", fmt.Errorf("message is nil") 55 } 56 slash := strings.LastIndex(any.TypeUrl, "/") 57 if slash < 0 { 58 return "", fmt.Errorf("message type url %q is invalid", any.TypeUrl) 59 } 60 return any.TypeUrl[slash+1:], nil 61 } 62 63 // MarshalAny takes the protocol buffer and encodes it into google.protobuf.Any. 64 func MarshalAny(pb proto.Message) (*Any, error) { 65 value, err := proto.Marshal(pb) 66 if err != nil { 67 return nil, err 68 } 69 return &Any{TypeUrl: googleApis + proto.MessageName(pb), Value: value}, nil 70 } 71 72 // DynamicAny is a value that can be passed to UnmarshalAny to automatically 73 // allocate a proto.Message for the type specified in a google.protobuf.Any 74 // message. The allocated message is stored in the embedded proto.Message. 75 // 76 // Example: 77 // 78 // var x ptypes.DynamicAny 79 // if err := ptypes.UnmarshalAny(a, &x); err != nil { ... } 80 // fmt.Printf("unmarshaled message: %v", x.Message) 81 type DynamicAny struct { 82 proto.Message 83 } 84 85 // Empty returns a new proto.Message of the type specified in a 86 // google.protobuf.Any message. It returns an error if corresponding message 87 // type isn't linked in. 88 func EmptyAny(any *Any) (proto.Message, error) { 89 aname, err := AnyMessageName(any) 90 if err != nil { 91 return nil, err 92 } 93 94 t := proto.MessageType(aname) 95 if t == nil { 96 return nil, fmt.Errorf("any: message type %q isn't linked in", aname) 97 } 98 return reflect.New(t.Elem()).Interface().(proto.Message), nil 99 } 100 101 // UnmarshalAny parses the protocol buffer representation in a google.protobuf.Any 102 // message and places the decoded result in pb. It returns an error if type of 103 // contents of Any message does not match type of pb message. 104 // 105 // pb can be a proto.Message, or a *DynamicAny. 106 func UnmarshalAny(any *Any, pb proto.Message) error { 107 if d, ok := pb.(*DynamicAny); ok { 108 if d.Message == nil { 109 var err error 110 d.Message, err = EmptyAny(any) 111 if err != nil { 112 return err 113 } 114 } 115 return UnmarshalAny(any, d.Message) 116 } 117 118 aname, err := AnyMessageName(any) 119 if err != nil { 120 return err 121 } 122 123 mname := proto.MessageName(pb) 124 if aname != mname { 125 return fmt.Errorf("mismatched message type: got %q want %q", aname, mname) 126 } 127 return proto.Unmarshal(any.Value, pb) 128 } 129 130 // Is returns true if any value contains a given message type. 131 func Is(any *Any, pb proto.Message) bool { 132 // The following is equivalent to AnyMessageName(any) == proto.MessageName(pb), 133 // but it avoids scanning TypeUrl for the slash. 134 if any == nil { 135 return false 136 } 137 name := proto.MessageName(pb) 138 prefix := len(any.TypeUrl) - len(name) 139 return prefix >= 1 && any.TypeUrl[prefix-1] == '/' && any.TypeUrl[prefix:] == name 140 } 141