ftp-server/src/connection.js

import _ from 'lodash'
import uuid from 'uuid'
import Promise from 'bluebird'
import { EventEmitter } from 'node:events'
import BaseConnector from './connector/base.js'
import { FileSystem } from './fs.js'
import Commands from './commands/index.js'
import errors from './errors.js'
import DEFAULT_MESSAGE from './messages.js'

export default class FtpConnection extends EventEmitter {
  constructor(server, options) {
    super()
    this.server = server
    this.id = uuid.v4()
    this.commandSocket = options.socket
    this.log = options.log.child({ id: this.id, ip: this.ip })
    this.commands = new Commands(this)
    this.transferType = 'binary'
    this.encoding = 'utf8'
    this.bufferSize = false
    this._restByteCount = 0
    this._secure = false

    this.connector = new BaseConnector(this)

    this.commandSocket.on('error', (err) => {
      this.log.error(err, 'Client error')
      this.server.emit('client-error', { connection: this, context: 'commandSocket', error: err })
    })
    this.commandSocket.on('data', this._handleData.bind(this))
    this.commandSocket.on('timeout', () => {
      this.log.trace('Client timeout')
      this.close()
    })
    this.commandSocket.on('close', () => {
      if (this.connector) this.connector.end()
      if (this.commandSocket && !this.commandSocket.destroyed) this.commandSocket.destroy()
      this.removeAllListeners()
    })
  }

  _handleData(data) {
    const messages = _.compact(data.toString(this.encoding).split('\r\n'))
    this.log.trace(messages)
    return Promise.mapSeries(messages, (message) => this.commands.handle(message))
  }

  get ip() {
    try {
      return this.commandSocket ? this.commandSocket.remoteAddress : undefined
    } catch (ex) {
      return null
    }
  }

  get restByteCount() {
    return this._restByteCount > 0 ? this._restByteCount : undefined
  }
  set restByteCount(rbc) {
    this._restByteCount = rbc
  }

  get secure() {
    return this.server.isTLS || this._secure
  }
  set secure(sec) {
    this._secure = sec
  }

  close(code = 421, message = 'Closing connection') {
    return Promise.resolve(code)
      .then((_code) => _code && this.reply(_code, message))
      .then(() => this.commandSocket && this.commandSocket.destroy())
  }

  login(username, password) {
    return Promise.try(() => {
      const loginListeners = this.server.listeners('login')
      if (!loginListeners || !loginListeners.length) {
        if (!this.server.options.anonymous) throw new errors.GeneralError('No "login" listener setup', 500)
      } else {
        return this.server.emitPromise('login', { connection: this, username, password })
      }
    }).then(({ root, cwd, fs, blacklist = [], whitelist = [] } = {}) => {
      this.authenticated = true
      this.commands.blacklist = _.concat(this.commands.blacklist, blacklist)
      this.commands.whitelist = _.concat(this.commands.whitelist, whitelist)
      this.fs = fs || new FileSystem(this, { root, cwd })
    })
  }

  reply(options = {}, ...letters) {
    const satisfyParameters = () => {
      if (typeof options === 'number') options = { code: options } // allow passing in code as first param
      if (!Array.isArray(letters)) letters = [letters]
      if (!letters.length) letters = [{}]
      return Promise.map(letters, (promise, index) => {
        return Promise.resolve(promise).then((letter) => {
          if (!letter) letter = {}
          else if (typeof letter === 'string') letter = { message: letter } // allow passing in message as first param

          if (!letter.socket) letter.socket = options.socket ? options.socket : this.commandSocket
          if (!options.useEmptyMessage) {
            if (!letter.message) letter.message = DEFAULT_MESSAGE[options.code] || 'No information'
            if (!letter.encoding) letter.encoding = this.encoding
          }
          return Promise.resolve(letter.message) // allow passing in a promise as a message
            .then((message) => {
              if (!options.useEmptyMessage) {
                const seperator = !options.hasOwnProperty('eol')
                  ? letters.length - 1 === index
                    ? ' '
                    : '-'
                  : options.eol
                    ? ' '
                    : '-'
                message = !letter.raw
                  ? _.compact([letter.code || options.code, message]).join(seperator)
                  : message
                letter.message = message
              } else {
                letter.message = ''
              }
              return letter
            })
        })
      })
    }

    const processLetter = (letter) => {
      return new Promise((resolve, reject) => {
        if (letter.socket && letter.socket.writable) {
          this.log.trace(
            { port: letter.socket.address().port, encoding: letter.encoding, message: letter.message },
            'Reply'
          )
          letter.socket.write(letter.message + '\r\n', letter.encoding, (error) => {
            if (error) {
              this.log.error('[Process Letter] Socket Write Error', { error: error.message })
              return reject(error)
            }
            resolve()
          })
        } else {
          this.log.trace({ message: letter.message }, 'Could not write message')
          reject(new errors.SocketError('Socket not writable'))
        }
      })
    }

    return satisfyParameters()
      .then((satisfiedLetters) =>
        Promise.mapSeries(satisfiedLetters, (letter, index) => {
          return processLetter(letter, index)
        })
      )
      .catch((error) => {
        this.log.error('Satisfy Parameters Error', { error: error.message })
      })
  }
}