RPC/TCP LogCabin protocol

Version 1

TCP message format:

type Message
    magic          ubint16 = 0xdaf4
    version        ubint16 = 1
    payload_length ubint32
    message_id     ubint64
    payload        [payload_length]byte:Payload

type Request:Payload
    version        uint8 = 1
    service        ubint16:ServiceId
    errorVersion   uint8:ServiceErrorVersion(service)
    opcode         ubint16

type Response:Payload
    status         uint8:Status

enum Status
    OK                     = 0
    SERVICE_SPECIFIC_ERROR = 1
    INVALID_VERSION        = 2
    INVALID_SERVICE        = 3
    INVALID_REQUEST        = 4

Security for LogCabin RPCs? Perhaps just use IPsec tunnels; need some magic scripts to configure.

Proposed version 2, encrypted transport

Still thinking; this probably is not a good design.

The syntax of the header is:

payload_length ulint32
timestamp      ulint32
zeros          [8]byte

eheader        [16]byte = AES-ECB(header)    
nonce          [24]byte
tag            [16]byte
payload        [payload_length]byte

where payload is an AES-GCM encrypted message.

magic = 'ad1b7beb'
digest = sha384('LogCabin RPC-over-TCP version 2').hexdigest()
print magic == digest[:8]