index.js

const express = require('express')
const qs = require('node:querystring')
const { randomUUID } = require('node:crypto')
const helmet = require('helmet')
const morgan = require('morgan')
const { URL } = require('node:url')
const session = require('express-session')
const RedisStore = require('connect-redis').default

const logger = require('../server/logger')
const redis = require('../server/redis')
const companion = require('../companion')
const { getCompanionOptions, generateSecret, buildHelpfulStartupMessage } = require('./helper')

/**
 * Configures an Express app for running Companion standalone
 *
 * @returns {object}
 */
module.exports = function server(inputCompanionOptions) {
  const companionOptions = getCompanionOptions(inputCompanionOptions)

  companion.setLoggerProcessName(companionOptions)

  if (!companionOptions.secret) companionOptions.secret = generateSecret('secret')
  if (!companionOptions.preAuthSecret) companionOptions.preAuthSecret = generateSecret('preAuthSecret')

  const app = express()

  const router = express.Router()

  if (companionOptions.server.path) {
    app.use(companionOptions.server.path, router)
  } else {
    app.use(router)
  }

  // Query string keys whose values should not end up in logging output.
  const sensitiveKeys = new Set(['access_token', 'uppyAuthToken'])

  /**
   * Obscure the contents of query string keys listed in `sensitiveKeys`.
   *
   * Returns a copy of the object with unknown types removed and sensitive values replaced by ***.
   *
   * The input type is more broad that it needs to be, this way typescript can help us guarantee that we're dealing with all
   * possible inputs :)
   *
   * @param {Record<string, any>} rawQuery
   * @returns {{
   *   query: Record<string, any>,
   *   censored: boolean
   * }}
   */
  function censorQuery(rawQuery) {
    /** @type {Record<string, any>} */
    const query = {}
    let censored = false
    Object.keys(rawQuery).forEach((key) => {
      if (typeof rawQuery[key] !== 'string') {
        return
      }
      if (sensitiveKeys.has(key)) {
        // replace logged access token
        query[key] = '********'
        censored = true
      } else {
        query[key] = rawQuery[key]
      }
    })
    return { query, censored }
  }

  router.use((request, response, next) => {
    const headerName = 'X-Request-Id'
		const oldValue = request.get(headerName);
    response.set(headerName, oldValue ?? randomUUID());

		next();
	})
  // log server requests.
  router.use(morgan('combined'))
  morgan.token('url', (req) => {
    const { query, censored } = censorQuery(req.query)
    return censored ? `${req.path}?${qs.stringify(query)}` : req.originalUrl || req.url
  })

  morgan.token('referrer', (req) => {
    const ref = req.headers.referer || req.headers.referrer
    if (typeof ref === 'string') {
      let parsed
      try {
        parsed = new URL(ref)
      } catch (_) {
        return ref
      }
      const rawQuery = qs.parse(parsed.search.replace('?', ''))
      const { query, censored } = censorQuery(rawQuery)
      return censored ? `${parsed.href.split('?')[0]}?${qs.stringify(query)}` : parsed.href
    }
    return undefined
  })

  // Use helmet to secure Express headers
  router.use(helmet.frameguard())
  router.use(helmet.xssFilter())
  router.use(helmet.noSniff())
  router.use(helmet.ieNoOpen())

  app.disable('x-powered-by')

  const sessionOptions = {
    secret: companionOptions.secret,
    resave: true,
    saveUninitialized: true,
  }

  const redisClient = redis.client(companionOptions)
  if (redisClient) {
    sessionOptions.store = new RedisStore({ client: redisClient, prefix: process.env.COMPANION_REDIS_EXPRESS_SESSION_PREFIX || 'companion-session:' })
  }

  if (process.env.COMPANION_COOKIE_DOMAIN) {
    sessionOptions.cookie = {
      domain: process.env.COMPANION_COOKIE_DOMAIN,
      maxAge: 24 * 60 * 60 * 1000, // 1 day
    }
  }

  // Session is used for grant redirects, so that we don't need to expose secret tokens in URLs
  // See https://github.com/transloadit/uppy/pull/1668
  // https://github.com/transloadit/uppy/issues/3538#issuecomment-1069232909
  // https://github.com/simov/grant#callback-session
  router.use(session(sessionOptions))

  // Routes
  if (process.env.COMPANION_HIDE_WELCOME !== 'true') {
    router.get('/', (req, res) => {
      res.setHeader('Content-Type', 'text/plain')
      res.send(buildHelpfulStartupMessage(companionOptions))
    })
  }

  // initialize companion
  const { app: companionApp } = companion.app(companionOptions)

  // add companion to server middleware
  router.use(companionApp)

  // WARNING: This route is added in order to validate your app with OneDrive.
  // Only set COMPANION_ONEDRIVE_DOMAIN_VALIDATION if you are sure that you are setting the
  // correct value for COMPANION_ONEDRIVE_KEY (i.e application ID). If there's a slightest possiblilty
  // that you might have mixed the values for COMPANION_ONEDRIVE_KEY and COMPANION_ONEDRIVE_SECRET,
  // please DO NOT set any value for COMPANION_ONEDRIVE_DOMAIN_VALIDATION
  if (process.env.COMPANION_ONEDRIVE_DOMAIN_VALIDATION === 'true' && process.env.COMPANION_ONEDRIVE_KEY) {
    router.get('/.well-known/microsoft-identity-association.json', (req, res) => {
      const content = JSON.stringify({
        associatedApplications: [
          { applicationId: process.env.COMPANION_ONEDRIVE_KEY },
        ],
      })
      res.header('Content-Length', `${Buffer.byteLength(content, 'utf8')}`)
      // use writeHead to prevent 'charset' from being appended
      // eslint-disable-next-line max-len
      // https://docs.microsoft.com/en-us/azure/active-directory/develop/howto-configure-publisher-domain#to-select-a-verified-domain
      res.writeHead(200, { 'Content-Type': 'application/json' })
      res.write(content)
      res.end()
    })
  }

  app.use((req, res) => {
    return res.status(404).json({ message: 'Not Found' })
  })

  app.use((err, req, res, next) => { // eslint-disable-line no-unused-vars
    if (app.get('env') === 'production') {
      // if the error is a URIError from the requested URL we only log the error message
      // to avoid uneccessary error alerts
      if (err.status === 400 && err.name === 'URIError') {
        logger.error(err.message, 'root.error', req.id)
      } else {
        logger.error(err, 'root.error', req.id)
      }
      res.status(500).json({ message: 'Something went wrong', requestId: req.id })
    } else {
      logger.error(err, 'root.error', req.id)
      res.status(500).json({ message: err.message, error: err, requestId: req.id })
    }
  })

  return { app, companionOptions }
}