Fix issue where dynamic challenges break if the decay is 0 (#2255)

* Fix issue where dynamic challenges break if the decay is 0
* Prevent users from adding a decay limit of 0 to dynamic value challenges

CTFd/plugins/dynamic_challenges/__init__.py

@@ -69,6 +69,11 @@ class DynamicValueChallenge(BaseChallenge):
             # We subtract -1 to allow the first solver to get max point value
             solve_count -= 1
 
+        # Handle situations where admins have entered a 0 decay
+        # This is invalid as it can cause a division by zero
+        if challenge.decay == 0:
+            challenge.decay = 1
+
         # It is important that this calculation takes into account floats.
         # Hence this file uses from __future__ import division
         value = (

CTFd/plugins/dynamic_challenges/assets/create.html

@@ -25,7 +25,7 @@
 			The amount of solves before the challenge reaches its minimum value
 		</small>
 	</label>
-	<input type="number" class="form-control" name="decay" placeholder="Enter decay limit" required>
+	<input type="number" class="form-control" name="decay" min="1" placeholder="Enter decay limit" required>
 </div>
 
 <div class="form-group">

CTFd/plugins/dynamic_challenges/assets/update.html

@@ -25,7 +25,7 @@
 			The amount of solves before the challenge reaches its minimum value
 		</small>
 	</label>
-	<input type="number" class="form-control chal-decay" name="decay" value="{{ challenge.decay }}" required>
+	<input type="number" class="form-control chal-decay" min="1" name="decay" value="{{ challenge.decay }}" required>
 </div>
 
 <div class="form-group">