[vnet] Fix IP2ME route creation logic for BITMAP VNET interface (#1284)

* [vnet] Fix IP2ME route creation logic for BITMAP VNET interface

Author: Volodymyr Samotiy

orchagent/intfsorch.cpp

@@ -1094,6 +1094,23 @@ void IntfsOrch::generateInterfaceMap()
     m_updateMapsTimer->start();
 }
 
+bool IntfsOrch::updateSyncdIntfPfx(const string &alias, const IpPrefix &ip_prefix, bool add)
+{
+    if (add && m_syncdIntfses[alias].ip_addresses.count(ip_prefix) == 0)
+    {
+        m_syncdIntfses[alias].ip_addresses.insert(ip_prefix);
+        return true;
+    }
+
+    if (!add && m_syncdIntfses[alias].ip_addresses.count(ip_prefix) > 0)
+    {
+        m_syncdIntfses[alias].ip_addresses.erase(ip_prefix);
+        return true;
+    }
+
+    return false;
+}
+
 void IntfsOrch::doTask(SelectableTimer &timer)
 {
     SWSS_LOG_ENTER();

orchagent/intfsorch.h

@@ -60,6 +60,8 @@ class IntfsOrch : public Orch
         return m_syncdIntfses;
     }
 
+    bool updateSyncdIntfPfx(const string &alias, const IpPrefix &ip_prefix, bool add = true);
+
 private:
 
     SelectableTimer* m_updateMapsTimer = nullptr;

orchagent/vnetorch.cpp

@@ -717,7 +717,7 @@ bool VNetBitmapObject::addIntf(const string& alias, const IpPrefix *prefix)
         intfMap_.emplace(alias, intfInfo);
     }
 
-    if (prefix)
+    if (prefix && gIntfsOrch->updateSyncdIntfPfx(alias, *prefix))
     {
         gIntfsOrch->addIp2MeRoute(gVirtualRouterId, *prefix);
     }
@@ -739,7 +739,7 @@ bool VNetBitmapObject::removeIntf(const string& alias, const IpPrefix *prefix)
 
     auto& intf = intfMap_.at(alias);
 
-    if (prefix)
+    if (prefix && gIntfsOrch->updateSyncdIntfPfx(alias, *prefix, false))
     {
         gIntfsOrch->removeIp2MeRoute(gVirtualRouterId, *prefix);
     }