Control node changes for supporting a knob to retain AS_PATH in a service chain.

The knob is in the service policy and translated by schema transformer into a
boolean in the service RIs for the control node. This is a per service-chain
knob.

Depends-On: Ia69b39bd5c615ba896d2919482467c6cd5e8f425
Closes-Jira-Bug: CEM-14977
Change-Id: I726f5c908b7c6f3bf8da7e89aaa297f5a6bbd381

Author: maheshmns

src/bgp/bgp_config.h

@@ -331,6 +331,7 @@ struct ServiceChainConfig {
     std::string source_routing_instance;
     std::string service_chain_id;
     bool sc_head;
+    bool retain_as_path;
 };
 
 struct StaticRouteConfig {

src/bgp/bgp_config_ifmap.cc

@@ -1015,6 +1015,7 @@ static void SetServiceChainConfig(BgpInstanceConfig *rti,
             inet_chain.source_routing_instance,
             inet_chain.service_chain_id,
             inet_chain.sc_head,
+            inet_chain.retain_as_path,
         };
         list.push_back(item);
     }
@@ -1032,6 +1033,7 @@ static void SetServiceChainConfig(BgpInstanceConfig *rti,
             inet6_chain.source_routing_instance,
             inet6_chain.service_chain_id,
             inet6_chain.sc_head,
+            inet6_chain.retain_as_path,
         };
         list.push_back(item);
     }
@@ -1049,6 +1051,7 @@ static void SetServiceChainConfig(BgpInstanceConfig *rti,
             evpn_chain.source_routing_instance,
             evpn_chain.service_chain_id,
             evpn_chain.sc_head,
+            evpn_chain.retain_as_path,
         };
         list.push_back(item);
     }
@@ -1066,6 +1069,7 @@ static void SetServiceChainConfig(BgpInstanceConfig *rti,
             evpnv6_chain.source_routing_instance,
             evpnv6_chain.service_chain_id,
             evpnv6_chain.sc_head,
+            evpnv6_chain.retain_as_path,
         };
         list.push_back(item);
     }

src/bgp/routing-instance/service_chaining.cc

@@ -265,7 +265,7 @@ template <typename T>
 ServiceChain<T>::ServiceChain(ServiceChainMgrT *manager,
     ServiceChainGroup *group, RoutingInstance *src, RoutingInstance *dest,
     RoutingInstance *connected, const vector<string> &subnets, AddressT addr,
-    bool head)
+    bool head, bool retain_as_path)
     : manager_(manager),
       group_(group),
       src_(src),
@@ -278,6 +278,7 @@ ServiceChain<T>::ServiceChain(ServiceChainMgrT *manager,
       dest_table_unregistered_(false),
       aggregate_(false),
       sc_head_(head),
+      retain_as_path_(retain_as_path),
       src_table_delete_ref_(this, src_table()->deleter()),
       dest_table_delete_ref_(this, dest_table()->deleter()),
       connected_table_delete_ref_(this, connected_table()->deleter()) {
@@ -816,6 +817,7 @@ void ServiceChain<T>::UpdateServiceChainRouteInternal(const RouteT *orig_route,
     bool load_balance_present = false;
     const Community *orig_community = NULL;
     const OriginVnPath *orig_ovnpath = NULL;
+    const AsPath *orig_aspath = NULL;
     RouteDistinguisher orig_rd;
     if (orig_route) {
         const BgpPath *orig_path = orig_route->BestPath();
@@ -828,6 +830,7 @@ void ServiceChain<T>::UpdateServiceChainRouteInternal(const RouteT *orig_route,
             ext_community = orig_attr->ext_community();
             orig_ovnpath = orig_attr->origin_vn_path();
             orig_rd = orig_attr->source_rd();
+            orig_aspath = orig_attr->as_path();
         }
         if (ext_community) {
             BOOST_FOREACH(const ExtCommunity::ExtCommunityValue &comm,
@@ -990,9 +993,16 @@ void ServiceChain<T>::UpdateServiceChainRouteInternal(const RouteT *orig_route,
         new_attr = attr_db->ReplaceOriginVnPathAndLocate(new_attr.get(),
             new_ovnpath);
 
-        // Strip aspath. This is required when the connected route is
-        // learnt via BGP.
-        new_attr = attr_db->ReplaceAsPathAndLocate(new_attr.get(), AsPathPtr());
+        // Strip as_path if needed. This is required when the connected route is
+        // learnt via BGP. If retain_as_path knob is configured replace the
+        // AsPath with the value from the original route.
+        if (retain_as_path() && orig_aspath) {
+            new_attr = attr_db->ReplaceAsPathAndLocate(new_attr.get(),
+                                                       orig_aspath);
+        } else {
+            new_attr = attr_db->ReplaceAsPathAndLocate(new_attr.get(),
+                                                       AsPathPtr());
+        }
 
         // If the connected path is learnt via XMPP, construct RD based on
         // the id registered with source table instead of connected table.
@@ -1786,7 +1796,7 @@ bool ServiceChainMgr<T>::LocateServiceChain(RoutingInstance *rtinstance,
     // Allocate the new service chain.
     ServiceChainPtr chain = ServiceChainPtr(new ServiceChainT(this, group,
         rtinstance, dest, connected_ri, config.prefix, chain_addr,
-        config.sc_head));
+        config.sc_head, config.retain_as_path));
 
     if (aggregate_host_route()) {
         ServiceChainT *obj = static_cast<ServiceChainT *>(chain.get());

src/bgp/routing-instance/service_chaining.h

@@ -143,7 +143,8 @@ class ServiceChain : public ConditionMatch {
 
     ServiceChain(ServiceChainMgrT *manager, ServiceChainGroup *group,
         RoutingInstance *src, RoutingInstance *dest, RoutingInstance *connected,
-        const std::vector<std::string> &subnets, AddressT addr, bool head);
+        const std::vector<std::string> &subnets, AddressT addr, bool head,
+        bool retain_as_path);
     Address::Family GetFamily() const { return manager_->GetFamily(); }
     Address::Family GetConnectedFamily() const {
         return manager_->GetConnectedFamily();
@@ -219,6 +220,7 @@ class ServiceChain : public ConditionMatch {
 
     bool aggregate_enable() const { return aggregate_; }
     bool is_sc_head() const { return sc_head_; }
+    bool retain_as_path() const { return retain_as_path_; }
     void set_aggregate_enable() { aggregate_ = true; }
     bool group_oper_state_up() const { return group_oper_state_up_; }
     void set_group_oper_state_up(bool up) { group_oper_state_up_ = up; }
@@ -239,6 +241,7 @@ class ServiceChain : public ConditionMatch {
     bool dest_table_unregistered_;
     bool aggregate_;  // Whether the host route needs to be aggregated
     bool sc_head_; // Whether this SI is at the head of the chain
+    bool retain_as_path_;
     LifetimeRef<ServiceChain> src_table_delete_ref_;
     LifetimeRef<ServiceChain> dest_table_delete_ref_;
     LifetimeRef<ServiceChain> connected_table_delete_ref_;

src/bgp/test/service_chain_test.cc

@@ -640,6 +640,8 @@ class ServiceChainTest : public ::testing::Test {
             extcomm_spec.communities.push_back(lb.GetExtCommunityValue());
 
         attr_spec.push_back(&extcomm_spec);
+
+
         BgpAttrPtr attr = bgp_server_->attr_db()->Locate(attr_spec);
 
         request.data.reset(new BgpTable::RequestData(attr, flags, label));
@@ -916,16 +918,23 @@ class ServiceChainTest : public ::testing::Test {
         const vector<uint32_t> sg_ids, const set<string> tunnel_encaps,
         const SiteOfOrigin &soo, const vector<uint32_t> &commlist,
         const vector<string> &origin_vn_path, const LoadBalance &lb,
-        const vector<int> tag_list) {
+        const vector<int> tag_list, bool retain_as_path=false) {
         BgpAttrPtr attr = path->GetAttr();
         if (attr->nexthop().to_v4().to_string() != path_id)
             return false;
         if (GetOriginVnFromRoute(path) != origin_vn)
             return false;
         if (label && path->GetLabel() != label)
             return false;
-        if (attr->as_path_count())
-            return false;
+        if (retain_as_path) {
+            if (!attr->as_path_count()) {
+                return false;
+            }
+        } else {
+            if (attr->as_path_count()) {
+                return false;
+            }
+        }
         if (sg_ids.size()) {
             vector<uint32_t> path_sg_ids = GetSGIDListFromRoute(path);
             if (path_sg_ids.size() != sg_ids.size())
@@ -1019,7 +1028,7 @@ class ServiceChainTest : public ::testing::Test {
         const SiteOfOrigin &soo, const vector<uint32_t> &commlist,
         const vector<string> &origin_vn_path,
         const LoadBalance &lb, const vector<int> tag_list,
-        bool replication=false) {
+        bool replication=false, bool retain_as_path=false) {
         task_util::TaskSchedulerLock lock;
         BgpRoute *route = RouteLookup(instance, prefix, replication);
         if (!route)
@@ -1036,7 +1045,7 @@ class ServiceChainTest : public ::testing::Test {
                 found = true;
                 if (MatchPathAttributes(path, path_id, origin_vn, label,
                     sg_ids, tunnel_encap, soo, commlist, origin_vn_path,
-                    lb, tag_list)) {
+                    lb, tag_list, retain_as_path)) {
                     break;
                 }
                 return false;
@@ -1063,14 +1072,14 @@ class ServiceChainTest : public ::testing::Test {
 
     void VerifyRouteAttributes(const string &instance,
         const string &prefix, const string &path_id, const string &origin_vn,
-        int label = 0, bool replication=false) {
+        int label = 0, bool replication=false, bool retain_as_path=false) {
         task_util::WaitForIdle();
         vector<string> path_ids = list_of(path_id);
         vector<uint32_t> commlist = list_of(CommunityType::AcceptOwnNexthop);
         TASK_UTIL_EXPECT_TRUE(CheckRouteAttributes(
             instance, prefix, path_ids, origin_vn, label, vector<uint32_t>(),
             set<string>(), SiteOfOrigin(), commlist, vector<string>(),
-            LoadBalance(), vector<int>(), replication));
+            LoadBalance(), vector<int>(), replication, retain_as_path));
     }
 
     void VerifyRouteAttributes(const string &instance, const string &prefix,
@@ -1263,9 +1272,10 @@ class ServiceChainTest : public ::testing::Test {
     }
 
     void SetServiceChainInformation(const string &instance,
-        const string &filename) {
+        const string &filename, bool retain_as_path=false) {
         auto_ptr<autogen::ServiceChainInfo> params = GetChainConfig(filename);
         params->sc_head = true;
+        params->retain_as_path = retain_as_path;
         ifmap_test_util::IFMapMsgPropertyAdd(&config_db_, "routing-instance",
             instance, sc_family_ == SCAddress::INET ?
                 "service-chain-information" : (sc_family_ == SCAddress::INET6 ?
@@ -3876,6 +3886,54 @@ TYPED_TEST(ServiceChainTest, ExtConnectRouteOriginVnUnresolved1) {
     this->DeleteConnectedRoute(NULL, this->BuildConnPrefix("1.1.2.3", 32));
 }
 
+//
+// Service chain route should be added for routes with unresolved origin
+// vn if there is at least one route target matching an export target of
+// the destination instance. Also AsPath should be retained.
+//
+// 1. Create Service Chain with 192.168.1.0/24 as vn subnet
+// 2. Add connected route
+// 3. Add MX leaked route 10.1.1.0/24 with unresolved OriginVn
+// 4. Verify that ext connect route 10.1.1.0/24 is added
+//
+TYPED_TEST(ServiceChainTest, ExtConnectRouteRetainAsPath1) {
+    if (this->GetFamily() == Address::EVPN) return;
+    vector<string> instance_names =
+        list_of("blue")("blue-i1")("red-i2")("red")("green");
+    multimap<string, string> connections =
+        map_list_of("blue", "blue-i1") ("red-i2", "red");
+    this->NetworkConfig(instance_names, connections);
+    this->VerifyNetworkConfig(instance_names);
+
+    this->SetServiceChainInformation("blue-i1",
+        "controller/src/bgp/testdata/service_chain_1.xml", true);
+
+    // Add Connected
+    this->AddConnectedRoute(NULL, this->BuildConnPrefix("1.1.2.3", 32), 100,
+                            this->BuildNextHopAddress("2.3.4.5"));
+
+    // Add Ext connect route with targets of both red and green.
+    this->AddVpnRoute(NULL, "red", this->BuildPrefix("10.1.1.0", 24), 100);
+
+    // Verify that MX leaked route is present in red
+    this->VerifyRouteExists("red", this->BuildPrefix("10.1.1.0", 24));
+
+    // Verify that ExtConnect route is present in blue
+    this->VerifyRouteExists("blue", this->BuildPrefix("10.1.1.0", 24));
+    this->VerifyRouteAttributes("blue", this->BuildPrefix("10.1.1.0", 24),
+                                this->BuildNextHopAddress("2.3.4.5"), "red",
+                                0, false, true);
+    this->VerifyRouteExists("blue",
+               this->BuildReplicationPrefix("10.1.1.0", 24), true);
+    this->VerifyRouteAttributes("blue",
+               this->BuildReplicationPrefix("10.1.1.0", 24),
+               this->BuildNextHopAddress("2.3.4.5"), "red", 0, true, true);
+
+    // Delete ExtRoute and connected route
+    this->DeleteVpnRoute(NULL, "red", this->BuildPrefix("10.1.1.0", 24));
+    this->DeleteConnectedRoute(NULL, this->BuildConnPrefix("1.1.2.3", 32));
+}
+
 //
 // Service chain route must not be added for routes with unresolved origin
 // vn if there is no route target matching an export target of destination