northd: make connected routes have higher priority than static

With this patch routes to connected networks have higher
priority than static routes with same ip_prefix.

This brings commonly-used behaviour for routes lookup order:
1: longest prefix match
2: metric

The metric has next lookup order:
1: connected routes
2: static routes

Earlier static and connected routes with same ip_prefix had
the same priority, so it was impossible to predict which one
is used for routing decision.

Each route's prefix length has its own 'slot' in lflow prios.
Now prefix length space is calculated using next information:
to calculate route's priority prefixlen multiplied by 3
+ route origin offset (0 - source-based route; 1 - static route;
2 - directly-connected route2).

Also, enlarge prio for generic records in lr_in_ip_routing stage
by 10000.

Signed-off-by: Vladislav Odintsov <odivlad@gmail.com>
Signed-off-by: Numan Siddique <numans@ovn.org>

northd/northd.c

@@ -309,6 +309,15 @@ enum ovn_stage {
  *
  */
 
+/*
+ * Route offsets implement logic to prioritize traffic for routes with
+ * same ip_prefix values:
+ *  -  connected route overrides static one;
+ *  -  static route overrides connected route. */
+#define ROUTE_PRIO_OFFSET_MULTIPLIER 3
+#define ROUTE_PRIO_OFFSET_STATIC 1
+#define ROUTE_PRIO_OFFSET_CONNECTED 2
+
 /* Returns an "enum ovn_stage" built from the arguments. */
 static enum ovn_stage
 ovn_stage_build(enum ovn_datapath_type dp_type, enum ovn_pipeline pipeline,
@@ -8830,6 +8839,7 @@ struct ecmp_groups_node {
     struct in6_addr prefix;
     unsigned int plen;
     bool is_src_route;
+    const char *origin;
     uint16_t route_count;
     struct ovs_list route_list; /* Contains ecmp_route_list_node */
 };
@@ -8867,6 +8877,7 @@ ecmp_groups_add(struct hmap *ecmp_groups,
     eg->prefix = route->prefix;
     eg->plen = route->plen;
     eg->is_src_route = route->is_src_route;
+    eg->origin = smap_get_def(&route->route->options, "origin", "");
     ovs_list_init(&eg->route_list);
     ecmp_groups_add_route(eg, route);
 
@@ -8967,19 +8978,20 @@ build_route_prefix_s(const struct in6_addr *prefix, unsigned int plen)
 static void
 build_route_match(const struct ovn_port *op_inport, const char *network_s,
                   int plen, bool is_src_route, bool is_ipv4, struct ds *match,
-                  uint16_t *priority)
+                  uint16_t *priority, int ofs)
 {
     const char *dir;
     /* The priority here is calculated to implement longest-prefix-match
      * routing. */
     if (is_src_route) {
         dir = "src";
-        *priority = plen * 2;
+        ofs = 0;
     } else {
         dir = "dst";
-        *priority = (plen * 2) + 1;
     }
 
+    *priority = (plen * ROUTE_PRIO_OFFSET_MULTIPLIER) + ofs;
+
     if (op_inport) {
         ds_put_format(match, "inport == %s && ", op_inport->json_key);
     }
@@ -9121,7 +9133,7 @@ add_ecmp_symmetric_reply_flows(struct hmap *lflows,
                   out_port->lrp_networks.ea_s,
                   IN6_IS_ADDR_V4MAPPED(&route->prefix) ? "" : "xx",
                   port_ip, out_port->json_key);
-    ovn_lflow_add_with_hint(lflows, od, S_ROUTER_IN_IP_ROUTING, 300,
+    ovn_lflow_add_with_hint(lflows, od, S_ROUTER_IN_IP_ROUTING, 10300,
                            ds_cstr(&match), ds_cstr(&actions),
                            &st_route->header_);
 
@@ -9151,8 +9163,10 @@ build_ecmp_route_flow(struct hmap *lflows, struct ovn_datapath *od,
     struct ds route_match = DS_EMPTY_INITIALIZER;
 
     char *prefix_s = build_route_prefix_s(&eg->prefix, eg->plen);
+    int ofs = !strcmp(eg->origin, ROUTE_ORIGIN_CONNECTED) ?
+        ROUTE_PRIO_OFFSET_CONNECTED: ROUTE_PRIO_OFFSET_STATIC;
     build_route_match(NULL, prefix_s, eg->plen, eg->is_src_route, is_ipv4,
-                      &route_match, &priority);
+                      &route_match, &priority, ofs);
     free(prefix_s);
 
     struct ds actions = DS_EMPTY_INITIALIZER;
@@ -9228,7 +9242,7 @@ add_route(struct hmap *lflows, struct ovn_datapath *od,
           const struct ovn_port *op, const char *lrp_addr_s,
           const char *network_s, int plen, const char *gateway,
           bool is_src_route, const struct ovsdb_idl_row *stage_hint,
-          bool is_discard_route)
+          bool is_discard_route, int ofs)
 {
     bool is_ipv4 = strchr(network_s, '.') ? true : false;
     struct ds match = DS_EMPTY_INITIALIZER;
@@ -9244,7 +9258,7 @@ add_route(struct hmap *lflows, struct ovn_datapath *od,
         }
     }
     build_route_match(op_inport, network_s, plen, is_src_route, is_ipv4,
-                      &match, &priority);
+                      &match, &priority, ofs);
 
     struct ds common_actions = DS_EMPTY_INITIALIZER;
     struct ds actions = DS_EMPTY_INITIALIZER;
@@ -9304,10 +9318,15 @@ build_static_route_flow(struct hmap *lflows, struct ovn_datapath *od,
         }
     }
 
+    int ofs = !strcmp(smap_get_def(&route->options, "origin", ""),
+                      ROUTE_ORIGIN_CONNECTED) ? ROUTE_PRIO_OFFSET_CONNECTED
+                                              : ROUTE_PRIO_OFFSET_STATIC;
+
     char *prefix_s = build_route_prefix_s(&route_->prefix, route_->plen);
     add_route(lflows, route_->is_discard_route ? od : out_port->od, out_port,
               lrp_addr_s, prefix_s, route_->plen, route->nexthop,
-              route_->is_src_route, &route->header_, route_->is_discard_route);
+              route_->is_src_route, &route->header_, route_->is_discard_route,
+              ofs);
 
     free(prefix_s);
 }
@@ -10721,14 +10740,14 @@ build_ip_routing_flows_for_lrouter_port(
             add_route(lflows, op->od, op, op->lrp_networks.ipv4_addrs[i].addr_s,
                       op->lrp_networks.ipv4_addrs[i].network_s,
                       op->lrp_networks.ipv4_addrs[i].plen, NULL, false,
-                      &op->nbrp->header_, false);
+                      &op->nbrp->header_, false, ROUTE_PRIO_OFFSET_CONNECTED);
         }
 
         for (int i = 0; i < op->lrp_networks.n_ipv6_addrs; i++) {
             add_route(lflows, op->od, op, op->lrp_networks.ipv6_addrs[i].addr_s,
                       op->lrp_networks.ipv6_addrs[i].network_s,
                       op->lrp_networks.ipv6_addrs[i].plen, NULL, false,
-                      &op->nbrp->header_, false);
+                      &op->nbrp->header_, false, ROUTE_PRIO_OFFSET_CONNECTED);
         }
     } else if (lsp_is_router(op->nbsp)) {
         struct ovn_port *peer = ovn_port_get_peer(ports, op);
@@ -10751,7 +10770,8 @@ build_ip_routing_flows_for_lrouter_port(
                               peer->lrp_networks.ipv4_addrs[0].addr_s,
                               laddrs->ipv4_addrs[k].network_s,
                               laddrs->ipv4_addrs[k].plen, NULL, false,
-                              &peer->nbrp->header_, false);
+                              &peer->nbrp->header_, false,
+                              ROUTE_PRIO_OFFSET_CONNECTED);
                 }
             }
         }
@@ -10822,7 +10842,7 @@ build_mcast_lookup_flows_for_lrouter(
         /* Drop IPv6 multicast traffic that shouldn't be forwarded,
          * i.e., router solicitation and router advertisement.
          */
-        ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_ROUTING, 550,
+        ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_ROUTING, 10550,
                       "nd_rs || nd_ra", "drop;");
         if (!od->mcast_info.rtr.relay) {
             return;
@@ -10850,23 +10870,23 @@ build_mcast_lookup_flows_for_lrouter(
             }
             ds_put_format(actions, "outport = \"%s\"; ip.ttl--; next;",
                           igmp_group->mcgroup.name);
-            ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_ROUTING, 500,
+            ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_ROUTING, 10500,
                           ds_cstr(match), ds_cstr(actions));
         }
 
         /* If needed, flood unregistered multicast on statically configured
          * ports. Otherwise drop any multicast traffic.
          */
         if (od->mcast_info.rtr.flood_static) {
-            ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_ROUTING, 450,
+            ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_ROUTING, 10450,
                           "ip4.mcast || ip6.mcast",
                           "clone { "
                                 "outport = \""MC_STATIC"\"; "
                                 "ip.ttl--; "
                                 "next; "
                           "};");
         } else {
-            ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_ROUTING, 450,
+            ovn_lflow_add(lflows, od, S_ROUTER_IN_IP_ROUTING, 10450,
                           "ip4.mcast || ip6.mcast", "drop;");
         }
     }

northd/ovn-northd.8.xml

@@ -3355,9 +3355,9 @@ output;
       table.  This table, instead, is responsible for determine the ECMP
       group id and select a member id within the group based on 5-tuple
       hashing.  It stores group id in <code>reg8[0..15]</code> and member id in
-      <code>reg8[16..31]</code>. This step is skipped with a priority-300 rule
-      if the traffic going out the ECMP route is reply traffic, and the ECMP
-      route was configured to use symmetric replies. Instead, the stored
+      <code>reg8[16..31]</code>. This step is skipped with a priority-10300
+      rule if the traffic going out the ECMP route is reply traffic, and the
+      ECMP route was configured to use symmetric replies. Instead, the stored
       <code>ct_label</code> value is used to choose the destination. The least
       significant 48 bits of the <code>ct_label</code> tell the destination MAC
       address to which the packet should be sent. The next 16 bits tell the
@@ -3373,14 +3373,14 @@ output;
     <ul>
       <li>
         <p>
-          Priority-550 flow that drops IPv6 Router Solicitation/Advertisement
+          Priority-10550 flow that drops IPv6 Router Solicitation/Advertisement
           packets that were not processed in previous tables.
         </p>
       </li>
 
       <li>
         <p>
-          Priority-500 flows that match IP multicast traffic destined to
+          Priority-10500 flows that match IP multicast traffic destined to
           groups registered on any of the attached switches and sets
           <code>outport</code> to the associated multicast group that will
           eventually flood the traffic to all interested attached logical
@@ -3390,7 +3390,7 @@ output;
 
       <li>
         <p>
-          Priority-450 flow that matches unregistered IP multicast traffic
+          Priority-10450 flow that matches unregistered IP multicast traffic
           and sets <code>outport</code> to the <code>MC_STATIC</code>
           multicast group, which <code>ovn-northd</code> populates with the
           logical ports that have
@@ -3404,10 +3404,11 @@ output;
         <p>
           IPv4 routing table.  For each route to IPv4 network <var>N</var> with
           netmask <var>M</var>, on router port <var>P</var> with IP address
-          <var>A</var> and Ethernet
-          address <var>E</var>, a logical flow with match <code>ip4.dst ==
-          <var>N</var>/<var>M</var></code>, whose priority is the number of
-          1-bits in <var>M</var>, has the following actions:
+          <var>A</var> and Ethernet address <var>E</var>, a logical flow with
+          match <code>ip4.dst == <var>N</var>/<var>M</var></code>, whose
+          priority is the number of 1-bits in <var>M</var> multiplied by 3 +
+          route offset: 0 for src-ip route policy, 1 for dst-ip static routes.
+          This flow has the following actions:
         </p>
 
         <pre>
@@ -3440,8 +3441,9 @@ next;
           <var>P</var> with IP address <var>A</var> and Ethernet address
           <var>E</var>, a logical flow with match in CIDR notation
           <code>ip6.dst == <var>N</var>/<var>M</var></code>,
-          whose priority is the integer value of <var>M</var>, has the
-          following actions:
+          whose priority is the integer value of <var>M</var> multiplied by 3 +
+          route offset: 0 for src-ip route policy, 1 for dst-ip static routes.
+          This flow has the following actions:
         </p>
 
         <pre>

tests/ovn-northd.at

@@ -5479,7 +5479,7 @@ check ovn-nbctl --wait=sb --ecmp-symmetric-reply lr-route-add lr0 1.0.0.1 192.16
 
 ovn-sbctl dump-flows lr0 > lr0flows
 AT_CHECK([grep -e "lr_in_ip_routing.*select" lr0flows | sed 's/table=../table=??/' | sort], [0], [dnl
-  table=??(lr_in_ip_routing   ), priority=65   , match=(ip4.dst == 1.0.0.1/32), action=(ip.ttl--; flags.loopback = 1; reg8[[0..15]] = 1; reg8[[16..31]] = select(1, 2);)
+  table=??(lr_in_ip_routing   ), priority=97   , match=(ip4.dst == 1.0.0.1/32), action=(ip.ttl--; flags.loopback = 1; reg8[[0..15]] = 1; reg8[[16..31]] = select(1, 2);)
 ])
 AT_CHECK([grep -e "lr_in_ip_routing_ecmp" lr0flows | sed 's/192\.168\.0\..0/192.168.0.??/' | sed 's/table=../table=??/' | sort], [0], [dnl
   table=??(lr_in_ip_routing_ecmp), priority=100  , match=(reg8[[0..15]] == 1 && reg8[[16..31]] == 1), action=(reg0 = 192.168.0.??; reg1 = 192.168.0.1; eth.src = 00:00:20:20:12:13; outport = "lr0-public"; next;)
@@ -5492,7 +5492,7 @@ check ovn-nbctl --wait=sb --ecmp-symmetric-reply lr-route-add lr0 1.0.0.1 192.16
 
 ovn-sbctl dump-flows lr0 > lr0flows
 AT_CHECK([grep -e "lr_in_ip_routing.*select" lr0flows | sed 's/table=../table=??/' | sort], [0], [dnl
-  table=??(lr_in_ip_routing   ), priority=65   , match=(ip4.dst == 1.0.0.1/32), action=(ip.ttl--; flags.loopback = 1; reg8[[0..15]] = 1; reg8[[16..31]] = select(1, 2);)
+  table=??(lr_in_ip_routing   ), priority=97   , match=(ip4.dst == 1.0.0.1/32), action=(ip.ttl--; flags.loopback = 1; reg8[[0..15]] = 1; reg8[[16..31]] = select(1, 2);)
 ])
 AT_CHECK([grep -e "lr_in_ip_routing_ecmp" lr0flows | sed 's/192\.168\.0\..0/192.168.0.??/' | sed 's/table=../table=??/' | sort], [0], [dnl
   table=??(lr_in_ip_routing_ecmp), priority=100  , match=(reg8[[0..15]] == 1 && reg8[[16..31]] == 1), action=(reg0 = 192.168.0.??; reg1 = 192.168.0.1; eth.src = 00:00:20:20:12:13; outport = "lr0-public"; next;)
@@ -5507,14 +5507,14 @@ check ovn-nbctl --wait=sb lr-route-add lr0 1.0.0.0/24 192.168.0.10
 ovn-sbctl dump-flows lr0 > lr0flows
 
 AT_CHECK([grep -e "lr_in_ip_routing.*192.168.0.10" lr0flows | sed 's/table=../table=??/' | sort], [0], [dnl
-  table=??(lr_in_ip_routing   ), priority=49   , match=(ip4.dst == 1.0.0.0/24), action=(ip.ttl--; reg8[[0..15]] = 0; reg0 = 192.168.0.10; reg1 = 192.168.0.1; eth.src = 00:00:20:20:12:13; outport = "lr0-public"; flags.loopback = 1; next;)
+  table=??(lr_in_ip_routing   ), priority=73   , match=(ip4.dst == 1.0.0.0/24), action=(ip.ttl--; reg8[[0..15]] = 0; reg0 = 192.168.0.10; reg1 = 192.168.0.1; eth.src = 00:00:20:20:12:13; outport = "lr0-public"; flags.loopback = 1; next;)
 ])
 
 check ovn-nbctl --wait=sb lr-route-add lr0 2.0.0.0/24 lr0-public
 
 ovn-sbctl dump-flows lr0 > lr0flows
 AT_CHECK([grep -e "lr_in_ip_routing.*2.0.0.0" lr0flows | sed 's/table=../table=??/' | sort], [0], [dnl
-  table=??(lr_in_ip_routing   ), priority=49   , match=(ip4.dst == 2.0.0.0/24), action=(ip.ttl--; reg8[[0..15]] = 0; reg0 = ip4.dst; reg1 = 192.168.0.1; eth.src = 00:00:20:20:12:13; outport = "lr0-public"; flags.loopback = 1; next;)
+  table=??(lr_in_ip_routing   ), priority=73   , match=(ip4.dst == 2.0.0.0/24), action=(ip.ttl--; reg8[[0..15]] = 0; reg0 = ip4.dst; reg1 = 192.168.0.1; eth.src = 00:00:20:20:12:13; outport = "lr0-public"; flags.loopback = 1; next;)
 ])
 
 AT_CLEANUP