RPC protocol (version 1)

Message types and sequence

Message types

• Getting nonce - Send client nonce and receives server nonce
• Authentication - Authenticate user
• Hello - Hello
• Hello return - Hello return
• First procedure invocation - First procedure invocation
• First procedure return - First procedure invocation return
• Next procedure invocation - Next procedure invocation
• Next procedure return - Nxt procedure invocation return

Message sequence

1. Client -> Server: Getting nonce
2. Server -> Client: Getting nonce return
3. [wait 3 * TCP RTT or 3 seconds] Server disconnects the connection
4. Client -> Server: Authentication
5. Server -> Server: Authentication return
6. [authentication fails] Server disconnects the connection
7. [If client invocates server procedure] 1. Client -> Server: First procedure invocation 1. Server -> Client: First procedure return 1. Client -> Server: Next procedure invocation 1. Server -> Client: Next procedure return 1. Client -> Server: Next procedure invocation 1. Server -> Client: Next procedure return 1. ...
8. [If server invocates client procedure] 1. Server -> Client: First procedure return 1. Client -> Server: First procedure invocation 1. Server -> Client: Next procedure return 1. Client -> Server: Next procedure invocation 1. Server -> Client: Next procedure return 1. Client -> Server: Next procedure invocation 1. ...
9. [every 10 seconds from client if there is no invocations b/w client and server] 1. Client -> Server: Hello 1. Server -> Client: Hello return
10. [after 20 seconds no message exchanges b/w client and server] 1. Server disconnections the connection

RPC HEADER

{ magic: uint32 // MAGIC, ver, endianess type: uint16 // type id: uint32 // message ID. Same ID for same invocation and return size: uint16 // total size including header }

magic

User can parse magic header and RPC protocol version and endianess

Magic header (Big endian) |--||--| 40c049

Magic header (Little endian) |--||--| 49c040

Protocol version (Big endian) |--||--| 01

Protocol version (Little endian) |--||--| 01

type

• 0 - Getting nonce
• 1 - Authentication
• 2 - Hello
• 3 - Hello return
• 4 - First procedure invocation
• 5 - First procedure return
• 6 - Next procedure invocation
• 7 - Next procedure return
• 8 - Error return

Authentication

Getting nonce

{ RPC_HEADER nonce: uint8[16] // Client side nonce hash: uint8[8] // hashing algorithm name }

Below is types of hashing algorithms

• " sha256" - SHA 256
• " sha51.2" - SHA 512

Getting nonce return

{ RPC_HEADER nonce: uint8[16] // Server side nonce }

Authentication

{ RPC_HEADER username: string password: uint8[...] // related to hashing algorithm }

This is how password is calculated salted_password = hash(RPC_MAGIC + password) password = hash(client_nonce + salted_password + server_nonce)

Authentication return

{ RPC_HEADER result: bool // Login succeed or not }

If authentication fails server will disconnect the connection just after send "Authentication return" message.

Hello

Hello

{ RPC_HEADER }

Hello return

{ RPC_HEADER }

First procedure

First procedure invocation

{ RPC_HEADER interface_name: char[RPC_MAX_NAME] interface_ver: uint32 procedure_name: char[RPC_MAX_NAME] return_type: uint8 argc: uint8 types: uint8[argc] args: ... // length depends on types }

First procedure return

{ RPC_HEADER interface_and_procedure_id: uint32 result: ... // length depends on return_type }

Next procedure

Next procedure invocation

{ RPC_HEADER interface_and_procedure_id: uint32 args: ... // length depends on types }

Next procedure return

{ RPC_HEADER result: ... // length depends on return_type }

Error

Error return

{ RPC_HEADER code: uint32 message: string }

Common error code and message

• 1 - There is no such interface named: xxx
• 2 - The version is not supported: nnn
• 3 - There is no such method named: xxx(a, b, c, d):r

Data type Encoding

void

data size: 0 bytes

bool

true: 1 false: 0 data size: 1 byte

uint8

data size: 1 byte

uint16

data size: 2 bytes

uint32

data size: 4 bytes

uint64

data size: 8 bytes

int8

data size: 1 byte

int16

data size: 2 bytes

int32

data size: 4 bytes

int64

data size: 8 bytes

float

data size: 4 bytes

double

data size: 8 bytes

string (type of uint8 array)

size: uint16 (including \0) data size: size

array

size: uint16 data size: primitive data size x size

License

GPL2 and Proprietary