[+] Simple hashtable rate limiter

src/main/kotlin/org/hydev/back/controller/FlowerController.kt

@@ -1,14 +1,13 @@
 package org.hydev.back.controller
 
-import org.hydev.back.P
+import org.hydev.back.*
 import org.hydev.back.db.Flower
 import org.hydev.back.db.FlowerRepo
-import org.hydev.back.getIP
-import org.hydev.back.str
 import org.springframework.web.bind.annotation.CrossOrigin
 import org.springframework.web.bind.annotation.GetMapping
 import org.springframework.web.bind.annotation.RequestMapping
 import org.springframework.web.bind.annotation.RestController
+import java.util.*
 import javax.servlet.http.HttpServletRequest
 
 @RestController
@@ -18,6 +17,35 @@ class FlowerController(
     private val flowerRepo: FlowerRepo
 )
 {
+    private final val LIMIT = 5
+    private lateinit var day: String
+    private lateinit var dayLimit: HashMap<String, Int>
+
+    init
+    {
+        initLimit()
+    }
+
+    final fun initLimit()
+    {
+        day = today().yyyymmdd()
+        dayLimit = HashMap()
+    }
+
+    /**
+     * Returns true if limit is reached
+     */
+    final fun checkLimit(token: str): bool
+    {
+        // Check whether limiter needs an update
+        if (day != today().yyyymmdd()) initLimit()
+
+        // Check limit
+        dayLimit[token]?.let { if (it >= LIMIT) return true }
+        dayLimit[token] = (dayLimit[token] ?: 0) + 1
+        return false
+    }
+
     @GetMapping("/get")
     fun get(@P id: str): Any
     {
@@ -31,7 +59,14 @@ class FlowerController(
     fun give(@P id: str, request: HttpServletRequest): Any
     {
         val id = id.lowercase()
-        println("[+] Flower added for $id by ${request.getIP()}")
+        val ip = request.getIP()
+
+        if (checkLimit("$id|$ip"))
+        {
+            println("[x] Flower rejected for $id by $ip: Daily limit reached")
+            return "Limit reached"
+        }
+        println("[+] Flower added for $id by $ip")
 
         var flower = flowerRepo.queryByPersonId(id)
         if (flower == null)
@@ -44,6 +79,6 @@ class FlowerController(
             flower.flowers += 1
             flowerRepo.save(flower)
         }
-        return "{}"
+        return ""
     }
 }