Protobuf Wire Format Simulation

[DuckSoft]

In this discussion thread we are going to discuss the implementation of Protobuf simulation.
From https://developers.google.com/protocol-buffers/docs/encoding#strings we can deduce that the Protobuf binary representation for our very simple GunMessage

message Gun {
   bytes Hunk = 1;
}

will become the following:

1. 0x0A, which can be rewritten into binary form 00001 (field number = 1) and 010 (wire type = 2, string/bytes);
2. Length encoded in LEB128 (https://developers.google.com/protocol-buffers/docs/encoding#varints);
3. The actual content.

PS: This is only pure guess from documentations. Let's validate this to give more insight.

[DuckSoft]

I've written a Proof of Concept (PoC) and validated my guess:

package pkg

import (
	"fmt"
	"github.com/Qv2ray/gun/pkg/proto"
	proto2 "github.com/golang/protobuf/proto"
	"testing"
)

func Test(t *testing.T) {
	message := &proto.Hunk{Data: []byte("shit")}
	marshal, err := proto2.Marshal(message)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%x", marshal)
}

When executed, the output is:

0a0473686974

This is to say my wild guess was correct!

[DuckSoft]

I've found some library (wheels) to implement an LEB128 encoding for us:
https://pkg.go.dev/github.com/go-interpreter/wagon/wasm/leb128

I think the Protobuf simulation theory is ready. Let's move to gRPC calling convention simulation.

[DuckSoft]

Got a better library for that!

https://github.com/Equim-chan/leb128