The Operator Foundation

Operator makes useable tools to help people around the world with censorship, security, and privacy.

Flower

Flower is a simple protocol for packet encapsulation. The Flower library can be integrated into Swift applications running on iOS or macOS. The intended use case is for macOS and iOS Network Extensions. A Network Extension is the Apple-approved way to create custom VPN protocols.

Usage

Obtain a Connection

The Flower library does not provide connections. A Connection must be obtained elsewhere, either a NWConnection from the Network framework or any transport Connection type from the Shapeshifter library.

Example using an NWConnection

import Network

let conn = NWConnection(host: NWEndpoint.Host("localhost"), port: NWEndpoint.Port(integerLiteral: 5555), using: .tcp)
conn.start(queue: .global())

Example using Shapeshifter transport Connection

import Shapeshifter-Swift-Transports

// Only use Rot13 transport for examples, never for real deployments.
let factory = Rot13ConnectionFactory((host: NWEndpoint.Host("localhost"), port: NWEndpoint.Port(integerLiteral: 5555))
let conn = factory.connect(using: .tcp)

Create Message objects

Create Message objects for encapsulated packets.

Example using IPv4 packet

import Flower

let data = Data(repeating: 0x00, count: 80)
let message = Message.IPDataV4(data)

Example using IPv6 packet

import Flower

let data = Data(repeating: 0x00, count: 80)
let message = Message.IPDataV6(data)

Send Message objects over Connection

Flower extends the Connection protocol to include the sendMessage function. You can call sendMessage on any Connection.

conn.sendMessage(message)
{
  maybeError in
  
  // Handle errors while attempting to send message
}

Read Message objects from Connection

Flower extends the Connection protocol to include the readMessages function. You can call readMessages on any Connection.

conn.readMessages
{
  message in
  
  switch message
  {
    case .IPDataV4(let data):
      print("Received an IPv4 packet")
    case .IPDataV6(let data):
      print("Receieved an IPv6 packet")
  }
}

The readMessages function only needs to be called once. It will call the provided callback multiple times, once for each packet received.