Question

I am using the below code to have HTTP Basic Auth in my app and
transform the response in case of Unauthorised access. It is not
working. Whats wrong here?

    // Http Basic Authentication 
    LiftRules.authentication = HttpBasicAuthentication("xxx") { 
      case (userName, userPass, _) => { 
        Console.println("Authenticating: " + userName) 
        User.find("userName", userName).map { 
          user => 
            if (user.password.isMatch(userPass)) { 
              Account.authenticatedUser.setFieldsFromDBObject(user.asDBObject) 
              userRoles(AuthRole("authorisedUser")) 
              Console.println("Success: " + userName) 
              true 
            } 
            else { 
              Console.println("Failed: " + userName) 
              false 
            } 
        } openOr false 
      } 
    } 

    LiftRules.responseTransformers.append { 
      resp => resp match { 
        case UnauthorizedResponse("xxx") => 
          Console.println("Responding modified..."); 
          JsonUnauthorizedResponse(("error" -> "Incorrect username or password")) 

        case x => Console.println("Responding..."); x 
      } 
    }

I am not getting the modified response for the URLs in RestApiHelper
object.
Can somebody please point me to how I can modify the response for the
Rest Api Urls in case of unauthorizedResponse. I do not intend to do
it using Status Codes. Since I am creating an API to be consumed by
mobile apps with server controlled error responses for consistency and
a lot of other factors.

Solution UPDATE:
This following overridden case class based on the answer by CheatEx worked for me:

  case class JsonHttpBasicAuthentication(realmName: String)(func: PartialFunction[(String, String, Req), Boolean]) extends HttpAuthentication {

  def credentials(r: Req): Box[(String, String)] = {
    header(r).flatMap(auth => {
      val decoded = new String(Base64.decodeBase64(auth.substring(6, auth.length).getBytes)).split(":").toList
      decoded match {
        case userName :: password :: _ => Full((userName, password))
        case userName :: Nil => Full((userName, ""))
        case _ => Empty
      }
    }
    )
  }

  override def realm = realmName

  def verified_? = {
    case (req) => {
      credentials(req) match {
        case Full((user, pwd)) if (func.isDefinedAt(user, pwd, req)) =>
          func(user, pwd, req)
        case _ => false
      }
    }
  }

  override def unauthorizedResponse: UnauthorizedResponse = new UnauthorizedResponse(realm) {
    override def toResponse = {
      val errResp: JValue = ("error" -> "Incorrect username or password")
      InMemoryResponse(errResp.toString.getBytes("UTF-8"),
      S.getHeaders(Nil), S.responseCookies, 200)
    }
  }
}

Answer 1

I had the same problem with the Lift’s default unauthorised response. My solution was to override unauthorizedResponse method of the HttpAuthentication trait.
Here is a code sample:

  private object MyHttpAuth extends HttpAuthentication {

    override def realm: String = "MyApp"

    def verified_? : PartialFunction[Req, Boolean] = {
      case req: Req => getUser(req) match {
        case Some(userId) => {
          userRoles(AuthRole(userId)::Nil)
          true
        }
        case None => false
      }
    }

    override def unauthorizedResponse: UnauthorizedResponse = new UnauthorizedResponse(realm) {
      override def toResponse = InMemoryResponse(Array(), Nil, Nil, 401)
    }
  }