[loopback]: skip route pointing to loopback interface (sonic-net#1570)

if we assign the loopback interface with non full-masked route, then we could
receive a route from fpmsyncd. we need to skip it otherwise, it will be queued
in orchagent.

    Dec 26 19:45:40.063448 vlab-01 INFO swss#orchagent: :- addRoute: Failed to get next hop ::@loopback0 for fc00:1::/64

Signed-off-by: Guohan Lu <lguohan@gmail.com>

orchagent/intfsorch.cpp

@@ -38,7 +38,6 @@ const int intfsorch_pri = 35;
 #define RIF_FLEX_STAT_COUNTER_POLL_MSECS "1000"
 #define UPDATE_MAPS_SEC 1
 
-#define LOOPBACK_PREFIX "Loopback"
 
 static const vector<sai_router_interface_stat_t> rifStatIds =
 {
@@ -57,7 +56,7 @@ IntfsOrch::IntfsOrch(DBConnector *db, string tableName, VRFOrch *vrf_orch) :
 {
  SWSS_LOG_ENTER();
 
- /* Initialize DB connectors */ 
+ /* Initialize DB connectors */
  m_counter_db = shared_ptr<DBConnector>(new DBConnector("COUNTERS_DB", 0));
  m_flex_db = shared_ptr<DBConnector>(new DBConnector("FLEX_COUNTER_DB", 0));
  m_asic_db = shared_ptr<DBConnector>(new DBConnector("ASIC_DB", 0));
@@ -576,7 +575,7 @@ void IntfsOrch::doTask(Consumer &consumer)
  SWSS_LOG_ERROR("Invalid mac argument %s to %s()", value.c_str(), e.what());
  continue;
  }
- } 
+ }
  else if (field == "nat_zone")
  {
  try

orchagent/routeorch.cpp

@@ -557,7 +557,13 @@ void RouteOrch::doTask(Consumer& consumer)
 
  for (auto alias : alsv)
  {
- if (alias == "eth0" || alias == "lo" || alias == "docker0")
+ /* skip route to management, docker, loopback
+ * TODO: for route to loopback interface, the proper
+ * way is to create loopback interface and then create
+ * route pointing to it, so that we can traps packets to
+ * CPU */
+ if (alias == "eth0" || alias == "docker0" ||
+ alias == "lo" || !alias.compare(0, strlen(LOOPBACK_PREFIX), LOOPBACK_PREFIX))
  {
  excp_intfs_flag = true;
  break;
@@ -1231,7 +1237,7 @@ bool RouteOrch::addRoute(RouteBulkContext& ctx, const NextHopGroupKey &nextHops)
  && vrf_id == gVirtualRouterId)
  {
  /* Only support the default vrf for Fine Grained ECMP */
- SWSS_LOG_INFO("Reroute %s:%s to fgNhgOrch", ipPrefix.to_string().c_str(), 
+ SWSS_LOG_INFO("Reroute %s:%s to fgNhgOrch", ipPrefix.to_string().c_str(),
  nextHops.to_string().c_str());
  return m_fgNhgOrch->addRoute(vrf_id, ipPrefix, nextHops);
  }

orchagent/routeorch.h

@@ -21,6 +21,8 @@
 /* Length of the Interface Id value in EUI64 format */
 #define EUI64_INTF_ID_LEN 8
 
+#define LOOPBACK_PREFIX "Loopback"
+
 typedef std::map<NextHopKey, sai_object_id_t> NextHopGroupMembers;
 
 struct NextHopGroupEntry