uci-socket/src/socket.js

// node modules
import { Server } from 'net'
import { unlink as fileDelete } from 'fs'
import { promisify } from 'util'
import path from 'path'
// npmjs modules
import mkdir from 'make-dir'
import btc from 'better-try-catch'
import _ON_DEATH from 'death' //this is intentionally ugly
import JSONStream from './json-stream'
import clone from 'clone'
// uci modules
import logger from '@uci/logger'
let log = {} // must declare here and set later for module wide access

// TODO change default pipe dir depending on OS linux,windows,mac
/** @constant {String} DEFAULT_PIPE_DIR
 * @description SOCKETS_DIR environment variable or '/tmp/UCI'
 */
const DEFAULT_PIPE_DIR = process.env.SOCKETS_DIR || '/tmp/UCI'
/** @constant {String} DEFAULT_SOCKET_NAME
 * @description for named pipe 'uci-sock' if not set in options  */
const DEFAULT_SOCKET_NAME = 'uci-sock'

/**
 * UCI Socket - class used to create a socket (server) that supports passing json packets
 * supports both named pipes and tcp sockets
 * also supports push of packets to all connected consumers (clients)
 * is extended from {@link https://nodejs.org/api/net.html#net_class_net_server | nodejs net.Server }
 * @extends Server
 */

class Socket extends Server {
  /**
   * UCI Socket class constructor
   * @param {Object} opts hash of options
   * @param {String} options.host  a tcp host name nornally not used as 0.0.0.0 is set by default
   * @param {String} options.port a tcp
   * @param {String | Boolean} options.path xeither full path to where socket should be created or if just 'true' then use default
   * @param {Boolean} options.clientTracking track connected clients for push notifications - default: true
   * @param {Object} options.conPacket A json operson's property
   *
   */
  constructor(opts = {}) {
    super()
    this.id = opts.id || opts.name || 'socket:' + new Date().getTime()
    if (!opts.path) {
      opts.host = opts.host || '0.0.0.0'
      opts.port = opts.port || 8080
    } else {
      if (typeof opts.path === 'boolean')
        opts.path = path.join(DEFAULT_PIPE_DIR, DEFAULT_SOCKET_NAME)
      if (path.dirname(opts.path) === '.')
        opts.path = path.join(DEFAULT_PIPE_DIR, opts.path)
    }
    this.clientTracking = opts.clientTracking || true
    this.clients = [] // track consumers (i.e. clients)
    this.opts = opts // for use to recover from selected errors
    //self bindings
    this._listen = this._listen.bind(this)
    this.create = this.create.bind(this)
    log = logger({
      file: 'src/socket.js',
      class: 'Socket',
      name: 'socket',
      id: this.id
    })
  } // end constructor

  /**
   * create - Description
   *
   * @returns {type} Description
   */
  async create() {
    return new Promise(async (resolve, reject) => {
      // set up a couple ways to gracefully destroy socket process is killed/aborted
      _ON_DEATH(async () => {
        log.info('\nhe\'s dead jim')
        await this._destroy()
      })
      process.once('SIGUSR2', async () => {
        await this._destroy
        process.kill(process.pid, 'SIGUSR2')
      })

      this.once('error', async err => {
        // recover from socket file that was not removed
        if (err.code === 'EADDRINUSE') {
          if (this.opts.path) {
            // if TCP socket should already be dead
            let [err, res] = await btc(promisify(fileDelete))(this.opts.path)
            if (!err) {
              log.info(
                { res: res, socket: this.opts.path },
                'socket already exists.....deleted'
              )
              return await this._listen(this.opts)
            }
            log.fatal(
              { err: err },
              'error deleting socket.  Can not establish a socket'
            )
            return err
          }
        }
        if (err.code === 'EACCES') {
          console.log(
            { socket: this.opts.path },
            'directory does not exist...creating'
          )
          await mkdir(path.dirname(this.opts.path))
          console.log({ socket: this.opts.path }, 'created')
          log.warn(
            { socket: this.opts.path },
            'directory does not exist...creating'
          )
          return await this._listen(this.opts)
        }
        // otherwise fatally exit
        log.info(err, 'creating socket')
        reject(err)
      })

      let [err, res] = await btc(this._listen)(this.opts)
      if (err) reject(err)
      resolve(res)
    }) // end creeate promise
  } // end create

  /**
   * registerPacketProcessor - Description
   * @public
   * @param {func} Description
   *
   */
  registerPacketProcessor(func) {
    this._packetProcess = func
  }

  /**
   * push - pushes a supplied UCI object packet to all connected clients
   *
   * @param {object} packet Description
   * @param {string} id  the header id string of the pushed packet, default: 'pushed'
   *
   */
  async push(packet, id) {
    packet._header = { id: id || 'pushed' }
    log.info(
      { opts: this.opts, packet: packet },
      'pushing a packet to all connected consumers'
    )
    this.clients.forEach(async client => {
      if (client.writable) {
        let [err, ser] = await btc(client.stream.serialize)(packet)
        if (err)
          ser = await client.stream.serialize({
            error: 'was not able to serialze the res packet',
            err: err,
            _header: { id: packet._header.id }
          })
        if (!id || id === client.ID) await this._send.bind(client)(ser)
      }
    })
  }

  async _listen(opts) {
    super.listen(opts, async (err, res) => {
      if (err) return err
      // this gets called for each client connection and is unique to each
      this.on('connection', async socket => {
        const stream = new JSONStream()
        socket.stream = stream // need this to track clients
        let send = this._send.bind(socket)
        if (this.clientTracking) this.clients.push(socket)
        // TODO add 'close' listener to socket to remove from this.clients
        log.info('new consumer connecting')
        log.info(await send(await stream.serialize({ _handshake: true })))
        if (this.opts.conPacket) {
          this.opts.conPacket._header = { id: 'pushed' }
          log.info(
            { conPacket: this.opts.conPacket },
            'pushing a preset command to just connected consumer'
          )
          send(await stream.serialize(this.opts.conPacket)) // send a packet command on to consumer on connection
        }
        socket.on('data', stream.onData)
        // TODO need to start error listener for stream so errors can be processed
        stream.on('message', messageProcess.bind(this, socket))

        async function messageProcess(client, packet) {
          log.info({ packet: packet }, 'incoming packet on socket side')
          let res = {}
          if (this.clientTracking && packet.clientID) {
            client.ID = packet.clientID
            res.cmd = 'ackID'
          } else {
            res = (await this._packetProcess(clone(packet))) || {}
            if (Object.keys(res).length === 0)
              res = {
                error:
                  'socket packet command function likely did not return a promise',
                packet: packet
              }
          }
          if (packet) {
            res._header = clone(packet._header, false) || {} //make sure return packet has header with id in case it was removed in processing
            delete packet._header // remove before adding to response header as request
          } else res._header = {}
          res._header.request = clone(packet, false)
          res._header.responder = { name: this.name, instanceID: this.id }
          res._header.socket = this.address()
          if (!res.cmd) res.cmd = 'reply' // by default return command is 'reply'
          let [err, ser] = await btc(stream.serialize)(res)
          if (err)
            ser = await stream.serialize({
              error: 'was not able to serialze the res packet',
              err: err,
              _header: { id: res._header.id }
            })
          log.info(await send(ser))
        } // end process message
      }) // end connecttion consumer
      log.info({ opts: this.opts }, 'socket created')
      return res
    }) // end super listen callback
  } // end listen

  async _destroy() {
    log.info('closing down socket')
    await this.close()
    log.info('all connections closed....exiting')
    process.exit()
  }

  // default packet process, just a simple echo
  async _packetProcess(packet) {
    return new Promise(resolve => {
      resolve(packet)
    })
  }

  // must have a consumer socket bound to use
  async _send(packet) {
    // timeout already set if sockect can't be drained in 10 secs
    return new Promise(resolve => {
      const cb = () => resolve('packet written to socket stream')
      if (!this.write(packet)) {
        this.once('drain', cb)
      } else {
        process.nextTick(cb)
      }
    })
  }
} // end class

export default Socket