Send a request to a default route using an IP whitelist/blacklist

const filterRoute = deter(
  {whitelist: ['127.0.0.1', '172.16.18.0/24', '::1']}, // ipv6! wow!
  onBadIp
)

const server = http.createServer(filterRoute(onGoodIp))

server.listen(8080)

function onBadIp(req, res) {
  res.statusCode = 403
  res.end()
}

function onGoodIp(req, res) {
  res.statusCode = 200
  res.end(`you're in!`)
}

deter(options, [defaultRoute], [lookup]) -> function

• options (object) an options object, with only one of the following keys; you can choose a whitelist or a blacklist, but not both:
  • whitelist (array) a list of CIDR strings that should be allowed through
  • blacklist (array) a list of CIDR strings that should be denied
• onFail (function) a route to be processed if a request fails the whitelist/blacklist. It will be passed all parameters sent through the route when called on failure.
• lookup (optional, function) a lookup function that gets the IP address from the request object; by default, this looks at any place the node http server might put an address (see the section on addresses for details). If you need to get an IP from a x-forwarded-for header, say, you can provide your own lookup function, with this form:
  • lookup(requestObject) -> ip (string)

• If you provide an invalid IP or CIDR in the whitelist/blacklist, the constructor will throw; if this is a problem for you, be sure to try/catch
• ipv6 is supported, including CIDR notation
• deter expects to route on a message whose first parameter is either a http.IncomingMessage or a net.Socket, conforming to the node.js HTTP/HTTPS and socket servers. It does not care what any of the other parameters are, and will pass them through to your route/failure function.
• Deter looks for addresses in the following places, which should cover all of the major node versions; you should be able to pass it your request or socket and have the right thing occur:
  • request.connection.remoteAddress
  • request.socket.remoteAddress
  • request.connection.socket.remoteAddress
  • socket.remoteAddress

If you need to look elsewhere for an address: don't fret, just provide your own lookup function:

const filterRoute = deter(
  {whitelist: ['127.0.0.1', '172.16.18.0/24']},
  onBadIp,
  lookup
)

const server = http.createServer(filterRoute(onGoodIp))

server.listen(8080)

function lookup(req) {
  if (req.headers && req.headers['x-forwarded-for']) {
    return req.headers['x-forwarded-for'].split(',')[0]
  }
}

Apache 2.0, see LICENSE for details.