Validation checks and diagnostics.

For following:
- If MPLS label is changing NH, then make sure non MCAST label does not point to
Composite NH of type L2 Comp.
- Temporarily store peer name in path.

Change-Id: I456ef6875e34f074a105f67e8e2866993e0ea30d
Partial-bug: #1548265

src/vnsw/agent/oper/agent_path.cc

@@ -39,7 +39,7 @@ AgentPath::AgentPath(const Peer *peer, AgentRoute *rt):
     is_subnet_discard_(false), dependant_rt_(rt), path_preference_(),
     local_ecmp_mpls_label_(rt), composite_nh_key_(NULL), subnet_service_ip_(),
     arp_mac_(), arp_interface_(NULL), arp_valid_(false),
-    ecmp_suppressed_(false) {
+    ecmp_suppressed_(false), peer_str_(peer ? peer->GetName() : "UNKNOWN") {
 }
 
 AgentPath::~AgentPath() {

src/vnsw/agent/oper/agent_path.h

@@ -344,6 +344,7 @@ class AgentPath : public Path {
     // by taking only one of the nexthop from the path
     bool ecmp_suppressed_;
     EcmpLoadBalance ecmp_load_balance_;
+    std::string peer_str_;
     DISALLOW_COPY_AND_ASSIGN(AgentPath);
 };
 

src/vnsw/agent/oper/mpls.cc

@@ -65,11 +65,20 @@ bool MplsTable::OnChange(DBEntry *entry, const DBRequest *req) {
     return ret;
 }
 
+void ValidateNH(const MplsLabel *mpls, NextHop *nh) {
+    CompositeNH *cnh = dynamic_cast<CompositeNH *>(nh);
+    if (!cnh)
+        return;
+    if (cnh->composite_nh_type() == Composite::L2COMP)
+        assert(mpls->GetType() == MplsLabel::MCAST_NH);
+}
+
 bool MplsTable::ChangeNH(MplsLabel *mpls, NextHop *nh) {
     if (mpls == NULL)
         return false;
 
     if (mpls->nh_ != nh) {
+        ValidateNH(mpls, nh);
         mpls->nh_ = nh;
         assert(nh);
         mpls->SyncDependentPath();