pcn-iptables: fix rule id check when inserting rule

Signed-off-by: Matteo Bertrone <m.bertrone@gmail.com>

Author: mbertrone

src/services/pcn-iptables/src/Chain.cpp

@@ -232,6 +232,10 @@ ChainInsertOutputJsonObject Chain::insert(ChainInsertInputJsonObject input) {
     id = input.getId();
   }
 
+  if (id > rules_.size()) {
+    throw std::runtime_error("id not allowed");
+  }
+
   auto newRule = std::make_shared<ChainRule>(*this, conf);
 
   ChainStatsJsonObject confStats;
@@ -1072,4 +1076,4 @@ void Chain::delRuleList() {
   if (parent_.interactive_) {
     applyRules();
   }
-}
+}