nwaku/examples/v1/example.nim

import
  confutils, chronicles, chronos, stew/byteutils, stew/shims/net as stewNet,
  eth/[keys, p2p],
  ../../waku/v1/protocol/waku_protocol,
  ../../waku/v1/node/waku_helpers,
  ../../waku/common/utils/nat,
  ./config_example

## This is a simple Waku v1 example to show the Waku v1 API usage.

const clientId = "Waku example v1"

proc run(config: WakuNodeConf, rng: ref HmacDrbgContext) =
  # Set up the address according to NAT information.
  let (ipExt, tcpPortExt, udpPortExt) = setupNat(config.nat, clientId,
    Port(config.tcpPort + config.portsShift),
    Port(config.udpPort + config.portsShift))
  # TODO: EthereumNode should have a better split of binding address and
  # external address. Also, can't have different ports as it stands now.
  let address = if ipExt.isNone():
                 Address(ip: parseIpAddress("0.0.0.0"),
                    tcpPort: Port(config.tcpPort + config.portsShift),
                    udpPort: Port(config.udpPort + config.portsShift))
                else:
                  Address(ip: ipExt.get(),
                    tcpPort: Port(config.tcpPort + config.portsShift),
                    udpPort: Port(config.udpPort + config.portsShift))

  # Create Ethereum Node
  var node = newEthereumNode(config.nodekey, # Node identifier
    address, # Address reachable for incoming requests
    NetworkId(1), # Network Id, only applicable for ETH protocol
    clientId, # Client id string
    addAllCapabilities = false, # Disable default all RLPx capabilities
    bindUdpPort = address.udpPort, # Assume same as external
    bindTcpPort = address.tcpPort, # Assume same as external
    rng = rng)

  node.addCapability Waku # Enable only the Waku protocol.

  # Set up the Waku configuration.
  let wakuConfig = WakuConfig(powRequirement: 0.002,
    bloom: some(fullBloom()), # Full bloom filter
    isLightNode: false, # Full node
    maxMsgSize: waku_protocol.defaultMaxMsgSize,
    topics: none(seq[waku_protocol.Topic]) # empty topic interest
    )
  node.configureWaku(wakuConfig)

  # Optionally direct connect to a set of nodes.
  if config.staticnodes.len > 0:
    connectToNodes(node, config.staticnodes)

  # Connect to the network, which will make the node start listening and/or
  # connect to bootnodes, and/or start discovery.
  # This will block until first connection is made, which in this case can only
  # happen if we directly connect to nodes (step above) or if an incoming
  # connection occurs, which is why we use a callback to exit on errors instead of
  # using `await`.
  # TODO: This looks a bit awkward and the API should perhaps be altered here.
  let connectedFut = node.connectToNetwork(
    true, # Enable listening
    false # Disable discovery (only discovery v4 is currently supported)
    )
  connectedFut.callback = proc(data: pointer) {.gcsafe.} =
    {.gcsafe.}:
      if connectedFut.failed:
        fatal "connectToNetwork failed", msg = connectedFut.readError.msg
        quit(1)

  # Using a hardcoded symmetric key for encryption of the payload for the sake of
  # simplicity.
  var symKey: SymKey
  symKey[31] = 1
  # Asymmetric keypair to sign the payload.
  let signKeyPair = KeyPair.random(rng[])

  # Code to be executed on receival of a message on filter.
  proc handler(msg: ReceivedMessage) =
    if msg.decoded.src.isSome():
      echo "Received message from ", $msg.decoded.src.get(), ": ",
        string.fromBytes(msg.decoded.payload)

  # Create and subscribe filter with above handler.
  let
    topic = [byte 0, 0, 0, 0]
    filter = initFilter(symKey = some(symKey), topics = @[topic])
  discard node.subscribeFilter(filter, handler)

  # Repeat the posting of a message every 5 seconds.
  # https://github.com/nim-lang/Nim/issues/17369
  var repeatMessage: proc(udata: pointer) {.gcsafe, raises: [Defect].}
  repeatMessage = proc(udata: pointer) =
    {.gcsafe.}:
      # Post a waku message on the network, encrypted with provided symmetric key,
      # signed with asymmetric key, on topic and with ttl of 30 seconds.
      let posted = node.postMessage(
        symKey = some(symKey), src = some(signKeyPair.seckey),
        ttl = 30, topic = topic, payload = @[byte 0x48, 0x65, 0x6C, 0x6C, 0x6F])

      if posted: echo "Posted message as ", $signKeyPair.pubkey
      else: echo "Posting message failed."

    discard setTimer(Moment.fromNow(5.seconds), repeatMessage)
  discard setTimer(Moment.fromNow(5.seconds), repeatMessage)

  runForever()

when isMainModule:
  let
    rng = keys.newRng()
    conf = WakuNodeConf.load()
  run(conf, rng)