NSE

Network Sequence Executor

About

NSE is a library that allow users to create a sequence of messages exchange between hosts. Messages are of TCP type and can be described with a custom protocol.

Configuration

Node

A node represents a host on the network. It is defined by:

• a list of tasks, which run in the background
• a sequence, which defines the ordered actions the node will perform

node:
  tasks: []
  sequence:

Tasks

Tasks are asynchronous, periodic actions that persist throughout the application's lifetime.
They are executed in parallel with the sequence.

Actions

Each entry in a node's sequence is called an action, defined by the required "action" key.
The fields associated with an action vary depending on its type. Each action must specify a protocol. The supported protocols currently are tcp and udp.

The supported actions are

• connect – establish a connection to a remote host
• disconnect – close a connection to a remote host
• bind – create a TCP server socket
• send – send a message (unicast or broadcast)
• wait – wait for an event to occur
• sleep – block the sequence for a given duration

connect

The connect action makes a socket connection to a remote host (or node).

action: connect
to:
  addr: 192.168.1.5
  port: 8000
timeout_ms: 5000

disconnect

The disconnect action disconnect the node from a remote host if a connection between the two exists.

action: disconnect
target:
  addr: 192.168.1.5
  port: 8000

bind

The bind action creates a TCP server on the given address and port.

action: bind
interface:
  addr: 192.168.1.4
  port: 8000
protocol: tcp

send

Sends a message either to specific remote hosts (unicast) or to a whole subnet (broadcast).

ℹ️ If the mode is unicast, an active connection (see connect) is required.

unicast

action: send
mode: unicast
protocol: tcp
from:
  addr: 192.168.0.1
to:
  - addr: 192.168.0.6
    port: 6900
buffer: [0x1, 0x1, 0x1]

broadcast

action: send
mode: broadcast
from:
  addr: 192.168.0.1
to:
  subnet: 192.168.0.0/24
buffer: [0x1, 0x1, 0x1]

sleep

The sleep event waits for a given amount of time before executing the next action.

action: sleep
duration_ms: 5000

wait

Blocks the sequence until a specified event occurs. Running tasks are not paused. Supported events are :

• sleep: pause for a duration
• messages: wait for specific incoming messages
• connection: wait for a remote client to connect

connection

Waits for one or more remote clients to connect to the local server.

action: wait
event: connection
protocol: tcp
connections:
  - from:
      addr: 192.168.1.2
    to:
      addr: 192.168.1.4
      port: 3000

messages

Waits for a list of incoming messages, optionally in a defined order.

• unordered: proceed when all messages are received, in any order.
• ordered: messages must arrive in the defined order; otherwise, the sequence is blocked until the timeout.

action: wait
event: messages
timeout: 5000
messages:
  order: unordered
  list:
    - from:
        addr: 192.168.0.6
        port: 6900
      to:
        addr: 192.168.0.1
        port: 6901
      protocol: udp
      buffer: [0x1, 0x1, 0x1]
      expect_response: false

Rust Implementation ideas

enum Action {
    Connect { to: Endpoint, timeout_ms: u64 },
    Disconnect { target: Endpoint },
    Bind { interface: Endpoint, protocol: Protocol },
    Send { mode: SendMode, from: Address, to: Vec<Endpoint>, buffer: Vec<u8> },
    Sleep { duration_ms: u64 },
    Wait { event: WaitEvent },
}

enum WaitEvent {
    Connection(Vec<ConnectionSpec>),
    Messages { order: OrderType, list: Vec<MessageMatch>, timeout_ms: Option<u64> }

Examples

1. Wait for a client

This example create a server on a local IP address and port. Once the client connects, the node sends a message to it.

node:
  tasks: []
  sequence:
    - action: bind
      interface:
        addr: 192.168.1.4
        port: 8000
      protocol: tcp

    - action: wait
      event: connection
      connections:
        - from:
            addr: 192.168.1.3
          to:
            addr: 192.168.1.4
            port: 8000
          protocol: tcp

    - action: send
      mode: unicast
      from:
        addr: 192.168.1.4
      to:
        - addr: 192.168.1.3
          port: 9999
      protocol: udp
      buffer: [0x1, 0x1, 0x1]