ripd: Implement `allow-ecmp X` command

[mirror_frr.git] / ripd / ripd.c

diff --git a/ripd/ripd.c b/ripd/ripd.c
index 48f266a94c2db41877ca3f9b80c8488c689d8733..3e8f8a934084eaaa7a591a412e45badce3a91b92 100644 (file)
--- a/ripd/ripd.c
+++ b/ripd/ripd.c
@@ -155,7 +155,10 @@ struct rip_info *rip_ecmp_add(struct rip *rip, struct rip_info *rinfo_new)
 {
        struct route_node *rp = rinfo_new->rp;
        struct rip_info *rinfo = NULL;
+       struct rip_info *rinfo_exist = NULL;
        struct list *list = NULL;
+       struct listnode *node = NULL;
+       struct listnode *nnode = NULL;
 
        if (rp->info == NULL)
                rp->info = list_new();
@@ -166,6 +169,33 @@ struct rip_info *rip_ecmp_add(struct rip *rip, struct rip_info *rinfo_new)
        if (listcount(list) && !rip->ecmp)
                return NULL;
 
+       /* Add or replace an existing ECMP path with lower neighbor IP */
+       if (listcount(list) && listcount(list) >= rip->ecmp) {
+               struct rip_info *from_highest = NULL;
+
+               /* Find the rip_info struct that has the highest nexthop IP */
+               for (ALL_LIST_ELEMENTS(list, node, nnode, rinfo_exist))
+                       if (!from_highest ||
+                           (from_highest &&
+                            IPV4_ADDR_CMP(&rinfo_exist->from,
+                                          &from_highest->from) > 0)) {
+                               from_highest = rinfo_exist;
+                       }
+
+               /* If we have a route in ECMP group, delete the old
+                * one that has a higher next-hop address. Lower IP is
+                * preferred.
+                */
+               if (rip->ecmp > 1 && from_highest &&
+                   IPV4_ADDR_CMP(&from_highest->from, &rinfo_new->from) > 0) {
+                       rip_ecmp_delete(rip, from_highest);
+                       goto add_or_replace;
+               }
+
+               return NULL;
+       }
+
+add_or_replace:
        rinfo = rip_info_new();
        memcpy(rinfo, rinfo_new, sizeof(struct rip_info));
        listnode_add(list, rinfo);
@@ -1171,6 +1201,12 @@ static void rip_response_process(struct rip_packet *packet, int size,
                        continue;
                }
 
+               if (packet->version == RIPv1 && rte->tag != 0) {
+                       zlog_warn("RIPv1 reserved field is nonzero: %d",
+                                 ntohs(rte->tag));
+                       continue;
+               }
+
                /* - is the destination address valid (e.g., unicast; not net 0
                   or 127) */
                if (!rip_destination_check(rte->prefix)) {
@@ -2625,6 +2661,36 @@ struct rip *rip_lookup_by_vrf_name(const char *vrf_name)
        return RB_FIND(rip_instance_head, &rip_instances, &rip);
 }
 
+/* Update ECMP routes to zebra when `allow-ecmp` changed. */
+void rip_ecmp_change(struct rip *rip)
+{
+       struct route_node *rp;
+       struct rip_info *rinfo;
+       struct list *list;
+       struct listnode *node, *nextnode;
+
+       for (rp = route_top(rip->table); rp; rp = route_next(rp)) {
+               list = rp->info;
+               if (list && listcount(list) > 1) {
+                       while (listcount(list) > rip->ecmp) {
+                               struct rip_info *from_highest = NULL;
+
+                               for (ALL_LIST_ELEMENTS(list, node, nextnode,
+                                                      rinfo)) {
+                                       if (!from_highest ||
+                                           (from_highest &&
+                                            IPV4_ADDR_CMP(
+                                                    &rinfo->from,
+                                                    &from_highest->from) > 0))
+                                               from_highest = rinfo;
+                               }
+
+                               rip_ecmp_delete(rip, from_highest);
+                       }
+               }
+       }
+}
+
 /* Create new RIP instance and set it to global variable. */
 struct rip *rip_create(const char *vrf_name, struct vrf *vrf, int socket)
 {
@@ -2634,7 +2700,7 @@ struct rip *rip_create(const char *vrf_name, struct vrf *vrf, int socket)
        rip->vrf_name = XSTRDUP(MTYPE_RIP_VRF_NAME, vrf_name);
 
        /* Set initial value. */
-       rip->ecmp = yang_get_default_bool("%s/allow-ecmp", RIP_INSTANCE);
+       rip->ecmp = yang_get_default_uint8("%s/allow-ecmp", RIP_INSTANCE);
        rip->default_metric =
                yang_get_default_uint8("%s/default-metric", RIP_INSTANCE);
        rip->distance =