Parse nested (opaque, any-typed) Protobuf message

Question

I have a message envelope:

import "google/protobuf/any.proto";

message Envelope {
    string type = 1;
    int32 version = 2;
    string message_id = 5;
    string timestamp = 6;
    google.protobuf.Any message = 7;
}

Now, I happen to know that the message is another Protobuf value with the following type: And a message defined as follows:

message Message {
    int32 value = 1;
    string name = 2;
}

Is it possible for me to do a one-shot parsing of this combined message? I am thinking that the problem with substituting Any with Message is the field numbering.

Answer 1

Any is just:

message Any {
  string type_url = 1;
  bytes value = 2;
}

where the value is just the regular payload content. If you know that the type is your Message, then you can use instead

message Envelope {
    string type = 1;
    int32 version = 2;
    string message_id = 5;
    string timestamp = 6;
    FakeAny message = 7;
}
message FakeAny {
  // don't even need to capture the type_url
  Message value = 2;
}
message Message {
    int32 value = 1;
    string name = 2;
}

and it should deserialize directly.