socketio-jwt/src/index.ts

import jwt from 'jsonwebtoken'
import { Socket } from 'socket.io'

class UnauthorizedError extends Error {
  public inner: { message: string }
  public data: { message: string, code: string, type: 'UnauthorizedError' }

  constructor (code: string, error: { message: string }) {
    super(error.message)
    this.message = error.message
    this.inner = error
    this.data = {
      message: this.message,
      code,
      type: 'UnauthorizedError'
    }
    Object.setPrototypeOf(this, UnauthorizedError.prototype)
  }
}

interface ExtendedError extends Error {
  data?: any
}

type SocketIOMiddleware = (
  socket: Socket,
  next: (err?: ExtendedError) => void
) => void

interface AuthorizeOptions {
  secret: string
}

export const authorize = (options: AuthorizeOptions): SocketIOMiddleware => {
  const { secret } = options
  return (socket, next) => {
    let token: string | null = null
    const authorizationHeader = socket.request.headers.authorization
    if (authorizationHeader != null) {
      const tokenSplitted = authorizationHeader.split(' ')
      if (tokenSplitted.length !== 2 || tokenSplitted[0] !== 'Bearer') {
        return next(
          new UnauthorizedError('credentials_bad_format', {
            message: 'Format is Authorization: Bearer [token]'
          })
        )
      }
      token = tokenSplitted[1]
    }
    if (token == null) {
      return next(
        new UnauthorizedError('credentials_required', {
          message: 'no token provided'
        })
      )
    }
    // Store encoded JWT
    socket = Object.assign(socket, { encodedToken: token })
    let payload: any
    try {
      payload = jwt.verify(token, secret)
    } catch {
      return next(
        new UnauthorizedError('invalid_token', {
          message: 'Unauthorized: Token is missing or invalid Bearer'
        })
      )
    }
    // Store decoded JWT
    socket = Object.assign(socket, { decodedToken: payload })
    return next()
  }
}