[intfsorch]: Fix issue with setting IP address in run time (#241)

Issue: sonic-net/SONiC#22
Issue was observed only when setting IP address via ifconfig
command. Caused by ifconfig command behavior: first it sets
IP address with netmask /8 and then changes netmask to specified
in command. Problem is not observed when set IP address with
"ip addr" command.
Introduced overlaps variable to check if the newly set IP prefix
has any overhaps with the current IP prefixes and wait until
there is no overlaps at all.

Author: oleksandrivantsiv

orchagent/intfsorch.cpp

@@ -87,33 +87,61 @@ void IntfsOrch::doTask(Consumer &consumer)
             }
 
             auto it_intfs = m_syncdIntfses.find(alias);
-            if (it_intfs == m_syncdIntfses.end() ||
-                !m_syncdIntfses[alias].ip_addresses.contains(ip_prefix.getIp()))
+            if (it_intfs == m_syncdIntfses.end())
             {
-                if (it_intfs == m_syncdIntfses.end())
+                if (addRouterIntfs(port))
                 {
-                    if (addRouterIntfs(port))
-                    {
-                        IntfsEntry intfs_entry;
-                        intfs_entry.ref_count = 0;
-                        m_syncdIntfses[alias] = intfs_entry;
-                    }
-                    else
-                    {
-                        it++;
-                        continue;
-                    }
+                    IntfsEntry intfs_entry;
+                    intfs_entry.ref_count = 0;
+                    m_syncdIntfses[alias] = intfs_entry;
+                }
+                else
+                {
+                    it++;
+                    continue;
                 }
-
-                addSubnetRoute(port, ip_prefix);
-                addIp2MeRoute(ip_prefix);
-
-                m_syncdIntfses[alias].ip_addresses.add(ip_prefix.getIp());
-                it = consumer.m_toSync.erase(it);
             }
-            else
+
+            if (m_syncdIntfses[alias].ip_addresses.count(ip_prefix))
+            {
                 /* Duplicate entry */
                 it = consumer.m_toSync.erase(it);
+                continue;
+            }
+
+            /* NOTE: Overlap checking is required to handle ifconfig weird behavior.
+             * When set IP address using ifconfig command it applies it in two stages.
+             * On stage one it sets IP address with netmask /8. On stage two it
+             * changes netmask to specified in command. As DB is async event to
+             * add IP address with original netmask may come before event to
+             * delete IP with netmask /8. To handle this we in case of overlap
+             * we should wait until entry with /8 netmask will be removed.
+             * Time frame between those event is quite small.*/
+            bool overlaps = false;
+            for (const auto &prefixIt: m_syncdIntfses[alias].ip_addresses)
+            {
+                if (prefixIt.isAddressInSubnet(ip_prefix.getIp()) ||
+                        ip_prefix.isAddressInSubnet(prefixIt.getIp()))
+                {
+                    overlaps = true;
+                    SWSS_LOG_NOTICE("Router interface %s IP %s overlaps with %s.", port.m_alias.c_str(),
+                            prefixIt.to_string().c_str(), ip_prefix.to_string().c_str());
+                    break;
+                }
+            }
+
+            if (overlaps)
+            {
+                /* Overlap of IP address network */
+                ++it;
+                continue;
+            }
+
+            addSubnetRoute(port, ip_prefix);
+            addIp2MeRoute(ip_prefix);
+
+            m_syncdIntfses[alias].ip_addresses.insert(ip_prefix);
+            it = consumer.m_toSync.erase(it);
         }
         else if (op == DEL_COMMAND)
         {
@@ -134,16 +162,16 @@ void IntfsOrch::doTask(Consumer &consumer)
 
             if (m_syncdIntfses.find(alias) != m_syncdIntfses.end())
             {
-                if (m_syncdIntfses[alias].ip_addresses.contains(ip_prefix.getIp()))
+                if (m_syncdIntfses[alias].ip_addresses.count(ip_prefix))
                 {
                     removeSubnetRoute(port, ip_prefix);
                     removeIp2MeRoute(ip_prefix);
 
-                    m_syncdIntfses[alias].ip_addresses.remove(ip_prefix.getIp());
+                    m_syncdIntfses[alias].ip_addresses.erase(ip_prefix);
                 }
 
                 /* Remove router interface that no IP addresses are associated with */
-                if (m_syncdIntfses[alias].ip_addresses.getSize() == 0)
+                if (m_syncdIntfses[alias].ip_addresses.size() == 0)
                 {
                     if (removeRouterIntfs(port))
                     {

orchagent/intfsorch.h

@@ -9,13 +9,14 @@
 #include "macaddress.h"
 
 #include <map>
+#include <set>
 
 extern sai_object_id_t gVirtualRouterId;
 extern MacAddress gMacAddress;
 
 struct IntfsEntry
 {
-    IpAddresses         ip_addresses;
+    std::set<IpPrefix>  ip_addresses;
     int                 ref_count;
 };