Microsoft Bond deserialization without knowing underlying schema

Question

I am looking at some network requests that are happening on my machine, and I recognize some as using the Microsoft Bond data serialization format. I want to deserialize the content of the request, but I do not have the schema that was used to create its content.

I know that with the ProtoBuf compiler, there is a way to output the content of a ProtoBuf-based binary file without the schema with something like:

protoc --decode_raw < data.proto

Is something similar available for Microsoft Bond? I am happy to write C#/C++ code to get that done, but curious if that is even possible.

For reference, the protocol is Compact Binary.

Answer 1

Thanks to some insights from Christopher Warrington, I was able to piece together the methodology through which a Bond-encoded Compact Binary content piece can be "unpacked" into its component pieces:

var ib = new Bond.IO.Unsafe.InputBuffer(File.ReadAllBytes("response_data.bin"));
var cbr = new CompactBinaryReader<Bond.IO.Unsafe.InputBuffer>(ib, 2);

cbr.ReadStructBegin();

BondDataType dt = BondDataType.BT_BOOL;
ushort id = 0;

while (dt != BondDataType.BT_STOP)
{
    cbr.ReadFieldBegin(out dt, out id);
    Console.WriteLine(dt + " " + id);
    if (dt == BondDataType.BT_STRING)
    {
        var stringValue = cbr.ReadString();
        Console.WriteLine(stringValue);
    }
    else if (dt == BondDataType.BT_LIST)
    {
        BondDataType listContent = BondDataType.BT_BOOL;
        int counter = 0;
        cbr.ReadContainerBegin(out counter, out listContent);
        Console.WriteLine("Inside container: " + listContent);
        if (listContent == BondDataType.BT_STRUCT)
        {
            BondDataType structDt = BondDataType.BT_BOOL;

            cbr.ReadStructBegin();
            while(structDt != BondDataType.BT_STOP)
            {
                cbr.ReadFieldBegin(out structDt, out id);
                Console.WriteLine(structDt + " " + id);
                if (structDt == BondDataType.BT_STRING)
                {
                    var stringValue = cbr.ReadString();
                    Console.WriteLine(stringValue);
                }
                else
                {
                    if (structDt != BondDataType.BT_STOP)
                    {
                        cbr.Skip(structDt);
                    }
                }
            }
            cbr.ReadStructEnd();
        }
        cbr.ReadContainerEnd();
    }
    else
    {
        if (dt != BondDataType.BT_STOP)
        {
            cbr.Skip(dt);
        }
    }
    cbr.ReadFieldEnd();
}

This is non-production code (you can spot many issues and lack of nested parsing) but it shows the approach through which one can get the contents.