Enforce rate limiting to control the frequency of user interactions
import play.api.mvc._
import play.api.libs.json._
class Application @Inject()(val controllerComponents: ControllerComponents) extends BaseController {
def postMessage = Action(parse.json) { request =>
val message = (request.body \\ "message").as[String]
// Processing the message
Ok("Message received.")
}
}
In the above Scala code, we have an endpoint
postMessage in the
Application controller. This endpoint accepts JSON requests and extracts a message string from the request body.
The vulnerability here is that there is no limitation or control over the frequency of requests that a user can send to this endpoint. This means an attacker could potentially send a large number of requests in a short period of time, causing a Denial of Service (DoS) attack by overloading the server.
This could also lead to other potential issues like resource exhaustion, where the server might run out of resources while trying to process a large number of requests. This could slow down the server significantly, affecting all users and not just the one sending the large number of requests.
In addition, if the processing of each message is resource-intensive or involves writing to a database, this could lead to further issues like database saturation or excessive disk usage.
This vulnerability can be mitigated by implementing a rate limiting mechanism, which would limit the number of requests a user can send to this endpoint within a certain period of time.
import play.api.mvc._
import play.api.libs.json._
import scala.concurrent.ExecutionContext
import akka.actor.ActorSystem
import scala.concurrent.duration._
import java.util.concurrent.TimeUnit
import javax.inject.Inject
import play.api.cache.AsyncCacheApi
class RateLimiter @Inject()(cache: AsyncCacheApi)(implicit system: ActorSystem, ec: ExecutionContext) {
def rateLimit(userId: String, limit: Int, within: FiniteDuration)(f: => Result): Result = {
val key = s"rateLimit:$userId"
val result = cache.get[Int](key).map {
case Some(count) if count >= limit =>
Results.TooManyRequests("You have exceeded your rate limit.")
case _ =>
cache.set(key, 1, within)
f
}
Await.result(result, Duration(5, TimeUnit.SECONDS))
}
}
class Application @Inject()(val controllerComponents: ControllerComponents, rateLimiter: RateLimiter) extends BaseController {
def postMessage = Action(parse.json) { request =>
val userId = request.headers.get("userId").getOrElse("anonymous")
rateLimiter.rateLimit(userId, 100, 1.hour) {
val message = (request.body \\ "message").as[String]
// Processing the message
Ok("Message received.")
}
}
}
The code above introduces a
RateLimiter class that uses Play's
AsyncCacheApi to track the number of requests made by each user. The
rateLimit method takes a
userId, a
limit (the maximum number of requests allowed within a certain time period), and a
within parameter (the time period), and a function
f that returns a
Result.
The
rateLimit method first checks if the user has already made
limit requests within the
within time period. If they have, it returns a
TooManyRequests result. If they haven't, it increments the user's request count in the cache and sets the cache to expire after the
within time period, then calls the function
f.
In the
Application controller, the
postMessage action now uses the
RateLimiter to limit the number of requests a user can make to 100 per hour. The
userId is taken from the request's headers, and if it's not present, the user is treated as "anonymous".
This solution effectively limits the rate at which users can post messages to the server, mitigating the risk of denial-of-service attacks and server resource exhaustion.