Change from type to bytes from string

[Kubuxu]

The string should be always valid UTF-8 data: see string type in the table https://developers.google.com/protocol-buffers/docs/proto#scalar

We are currently sending binary multihash over it. There are some other mistakes like that in IPFS proto files. There might be more in this file.

[jbenet]

sgtm. @diasdavid ?

[daviddias]

Yes! :) The same problem is happening in the Bitswap Message proto -- https://github.com/ipfs/go-ipfs/blob/master/exchange/bitswap/message/pb/message.proto#L8 --, can we get that changed as well? We are already patching it by having a different proto file for js-ipfs.

Shouldn't the Go serializer catch this?

@Kubuxu Will you be able to fix both these issues before 0.4.5? Can you keep me up to date?

[whyrusleeping]

string and bytes are aliases as far as protobuf is concerned. This is simply a problem with the json marshaling code for the commands lib. We need to instruct it on how to marshal binary data

[Kubuxu]

If we adhere to what protobuf recommends (binary data in bytes, valid utf-8 in string) then all our marshalling problems will go away as emitted structure will be []byte and it will get base64 encoded by the native Go JSON marshaller.