Problem with RPC: Add abilty to exclude certain types/ methods

[lu4p]

When I garble the ToRat client, compiling works even with cgo (many thanks).
However I communicate over RPC with the server and the server needs the API function names to stay the same.

I get the following error when a garbled client connects:
"Invalid Hostname rpc: can't find service API.Hostname"

Client RPC Api definition: https://github.com/lu4p/ToRat/blob/master/torat_client/rpcapi.go
Example Server RPC Call: https://github.com/lu4p/ToRat/blob/c23e742bc5937c40320bf437479cd7083c83e78d/torat_server/shell.go#L199

Any Ideas on how certain types and their methods could be excluded?

[mvdan]

The methods are exported, so they shouldn't be getting randomized. This is because of interfaces.

The type API is exported, but that doesn't affect interfaces, so we do randomize that name. I assume that's where your problem arises:

	rpc.Register(api)

This is good old reflect, so there's no way we can detect this. We could give up and never garble exported types, but that would be pretty flawed.

I'm not a big fan of special comments telling tools what to do, so I'd rather not add something like //go:garble off. When looking at the source statically, at the moment, there's no way to tell that you need the API name to remain as-is, unless we special case what rpc.Register does. That would work for your use case, but it wouldn't work for others.

Something that comes to mind is having garble not touch a type T, if one does reflect.TypeOf(t) where t has type T. Since we garble one package at a time, we would only search for such TypeOf calls in the package where T is defined. So, in your case, you could add something like:

// Make sure API is never garbled.
var _ = reflect.TypeOf(API{})

[lu4p]

Will try the workaround.

[mvdan]

If you mean the reflect.TypeOf line, that won't work. It's just an idea I was suggesting outloud.

[lu4p]

I thought this is implemented already, my bad

[cytown]

It's a must feature. Especially we can use garble to build a plugin.

[mvdan]

@cytown plugins already work, if you avoid building separate files as per #19. If they don't work, please file a separate issue as it doesn't seem related to this one.