Wrap requests?

[Scott Stewart]

Hi, 

I was hoping to use unfiltered to define a servlet filter that adds a value to the request as a cookie or header which could then be used in front of a servlet to gain access to this value. I'd prefer not to use a session to pass the value. I was thinking something like HttpServletRequestWrapper but I don't see how I could do this with a unfiltered.filter.Plan. I searched on variants of 'unfiltered wrap http request' but didn't find a similar scenario. Does anyone know if something like this is possible? 

Thanks -Scott

[Doug Tangren]

On Fri, Jan 9, 2015 at 12:33 AM, Scott Stewart <scotts...@gmail.com> wrote:

Hi, 

I was hoping to use unfiltered to define a servlet filter that adds a value to the request as a cookie or header which could then be used in front of a servlet to gain access to this value. I'd prefer not to use a session to pass the value. I was thinking something like HttpServletRequestWrapper but I don't see how I could do this with a unfiltered.filter.Plan. I searched on variants of 'unfiltered wrap http request' but didn't find a similar scenario. Does anyone know if something like this is possible? 

With filter.Plans the main interfaces is a partial function whose input is an unfiltered request that wraps an underlying http servlet request. With the underlying http servlet request you could wrap it in a HttpServletRequestWrapper, extend what you need, then wrap another plan. Below is some pseudo code

def wrap(p: Plan): Plan = Planify {

   case req => 

      val newReq = new HttpServletRequestWrapper(req) {

          ...

      }

      p.intent.lift(newReq).getOrElse(Pass)

}

Http(...).plan(wrap(plan))

 

Thanks -Scott

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[Scott Stewart]

Thanks for the reply but req is a unfiltered.request.HttpRequest and can't be wrapped by HttpServletRequestWrapper, right? I'm sure there's some way..

[Doug Tangren]

On Mon, Jan 12, 2015 at 12:44 PM, Scott Stewart <scotts...@gmail.com> wrote:

Thanks for the reply but req is a unfiltered.request.HttpRequest and can't be wrapped by HttpServletRequestWrapper, right? I'm sure there's some way..

Sorry, Try new HttpServletRequestWrapper(req.underlying).

[Scott Stewart]

That works, but Plan.Intent is a Cycle.Intent[HttpServletRequest,HttpServletResponse] which is a PartialFunction[HttpRequest[HttpServletRequest], ResponseFunction[HttpServletResponse]] so lift(..) rejects the newReq. Maybe something like 

p.intent.lift(new RequestBinding(newReq)).getOrElse(Pass), but I'm still trying to wrap my head around how this would work

[Scott Stewart]

Ended up writing my own Plan that takes use of a special ResponseFunction because I wanted to be able to swap out a request within an intent like this:

    case class MyPrincipal(user: String) extends Principal { def getName = user; }

    def getUser(cookie: String): Option[String] = Some("dummyUser")

    val userAuthPlan = new PlanWithRequestSwap {
      def intent = {
        case req @ Cookies(cookies) => cookies(authCookieName) match {
          case Some(Cookie(_,authToken,_,_,_,_,_,_)) => getUser(authToken) match {
            case Some(user) =>
              println("got user: "+ user)
              RequestSwap(new RequestBinding(new HttpServletRequestWrapper(req.underlying) {
                override def getUserPrincipal = new MyPrincipal(user)
              }))
            case _ => Unauthorized
          }
          case _ => Unauthorized
        }
      }
    } 

    val userProtectedPlan = Planify {
      case req => req.underlying.getUserPrincipal match {
        case MyPrincipal(user) => req match {
          case Path("/userProtected") => HtmlBody(s"get protected as $user")
        }
        case x => Unauthorized ~> HtmlBody(s"Unrecognized principal: $x")
      }
    }

so I ended up with this:

case class RequestSwap(req: RequestBinding) extends ResponseFunction[Any] { def apply[T](res: HttpResponse[T]) = res; }
 
trait PlanWithRequestSwap extends Plan {
  override def doFilter(request: ServletRequest,
                        response: ServletResponse,
                        chain: FilterChain) {
    (request, response) match {
      case (hreq: HttpServletRequest, hres: HttpServletResponse) =>
        val request = new RequestBinding(hreq)
        val response = new ResponseBinding(hres)
 
        intent.lift(request) match {
          case Some(rf:RequestSwap) => chain.doFilter(rf.req.underlying, response.underlying)
          case Some(Pass) | None => chain.doFilter(request.underlying, response.underlying)
          case Some(rf) => rf(response).outputStream.close()
        }
     }
  }
}

I can run a server like the following but it will ultimately be exported as a servlet filter in front of more traditional java web apps:

    val publicPlan = Planify { 
      case Path(Seg("setc"::name::value::Nil)) => SetCookies(Cookie(name, value, path=Some("/"))) ~> HtmlBody(s"set $name=$value")
    }
 
    unfiltered.jetty.Server.local(9080).plan(publicPlan).plan(userAuthPlan).plan(userProtectedPlan).run()

The full file is https://gist.github.com/scottstewartt/5a0d47d11c8d21dd062b and thanks again for your help and please don't hesitate to point out problems
-Scott