pim-kat: changed kat handling to match rfc-4601 more closely.

1. This is needed to layout the MSDP macros for determining what SAs are
originated by a MSDP speaker.
2. We no longer let the kat timer expire on an active flow. Activity
counters/lastuse is polled via a wheel for every SG entry. If new
activity is detected the keepalive timer is started and SPT bit set.
A SRC_STREAM reference is also created for the entry if one doesn't
already exist.
3. If KAT actually expires it means the flow is no longer active. At
this point we stop advertising the SA to MSDP peers. We also pull
the SRC_STREAM reference (deleting the entry if there are no other
references).

PS: Checking counters on KAT expiry will come in the next change.

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>
Acked-by: Donald Sharp <sharpd@cumulusnetworks.com>

1 files changed, 78 insertions, 40 deletions

diff --git a/pimd/pim_msdp.c b/pimd/pim_msdp.c
index 76127245ce..12f363e6fe 100644
--- a/pimd/pim_msdp.c
+++ b/pimd/pim_msdp.c
@@ -36,6 +36,7 @@
 #include "pim_rp.h"
 #include "pim_str.h"
 #include "pim_time.h"
+#include "pim_upstream.h"
 
 #include "pim_msdp.h"
 #include "pim_msdp_packet.h"
@@ -139,10 +140,6 @@ pim_msdp_sa_upstream_del(struct pim_msdp_sa *sa)
   }
 
   sa->up = NULL;
-  /* XXX: we can't pull the plug on an active flow even if the SA entry is
-   * removed. so ideally we want to start the kat in parallel and let the
-   * entry age out; but running the kat has fatal consequences. need to
-   * check with Donald on the best way to go abt this */
   if (PIM_UPSTREAM_FLAG_TEST_SRC_MSDP(up->flags)) {
     PIM_UPSTREAM_FLAG_UNSET_SRC_MSDP(up->flags);
     pim_upstream_del(up, __PRETTY_FUNCTION__);
@@ -158,12 +155,6 @@ pim_msdp_sa_upstream_del(struct pim_msdp_sa *sa)
 static bool
 pim_msdp_sa_upstream_add_ok(struct pim_msdp_sa *sa, struct pim_upstream *xg_up)
 {
-  if (sa->flags & PIM_MSDP_SAF_LOCAL) {
-    /* if there is a local reference we should NEVER use it for setting up
-     * SPTs otherwise we will get stuck in a simple circular deadlock */
-    return false;
-  }
-
   if (!(sa->flags & PIM_MSDP_SAF_PEER)) {
     /* SA should have been rxed from a peer */
     return false;
@@ -194,10 +185,9 @@ pim_msdp_sa_upstream_add_ok(struct pim_msdp_sa *sa, struct pim_upstream *xg_up)
 
 /* Upstream add evaluation needs to happen everytime -
  * 1. Peer reference is added or removed.
- * 2. Local reference is added or removed.
- * 3. The RP for a group changes.
- * 4. joinDesired for the associated (*, G) changes
- * 5. associated (*, G) is removed - this seems like a bit redundant
+ * 2. The RP for a group changes.
+ * 3. joinDesired for the associated (*, G) changes
+ * 4. associated (*, G) is removed - this seems like a bit redundant
  *    (considering #4); but just in case an entry gets nuked without
  *    upstream state transition
  *    */
@@ -359,12 +349,17 @@ static void
 pim_msdp_sa_deref(struct pim_msdp_sa *sa, enum pim_msdp_sa_flags flags)
 {
   char key_str[PIM_MSDP_SA_KEY_STRLEN];
+  bool update_up = false;
 
-  pim_msdp_sa_key_dump(sa, key_str, sizeof(key_str), true);
+  if (PIM_DEBUG_MSDP_EVENTS) {
+    pim_msdp_sa_key_dump(sa, key_str, sizeof(key_str), true);
+  }
 
   if ((sa->flags &PIM_MSDP_SAF_LOCAL)) {
     if (flags & PIM_MSDP_SAF_LOCAL) {
-      zlog_debug("%s local reference removed", key_str);
+      if (PIM_DEBUG_MSDP_EVENTS) {
+        zlog_debug("%s local reference removed", key_str);
+      }
       if (msdp->local_cnt)
         --msdp->local_cnt;
     }
@@ -372,13 +367,21 @@ pim_msdp_sa_deref(struct pim_msdp_sa *sa, enum pim_msdp_sa_flags flags)
 
   if ((sa->flags &PIM_MSDP_SAF_PEER)) {
     if (flags & PIM_MSDP_SAF_PEER) {
-      zlog_debug("%s peer reference removed", key_str);
+      if (PIM_DEBUG_MSDP_EVENTS) {
+        zlog_debug("%s peer reference removed", key_str);
+      }
       pim_msdp_sa_state_timer_setup(sa, false /* start */);
+      /* if peer ref was removed we need to remove the msdp reference on the
+       * msdp entry */
+      update_up = true;
     }
   }
 
   sa->flags &= ~flags;
-  pim_msdp_sa_upstream_update(sa, NULL /* xg_up */, "sa-deref");
+  if (update_up) {
+    pim_msdp_sa_upstream_update(sa, NULL /* xg_up */, "sa-deref");
+  }
+
   if (!(sa->flags & PIM_MSDP_SAF_REF)) {
     pim_msdp_sa_del(sa);
   }
@@ -424,27 +427,53 @@ pim_msdp_sa_ref(struct pim_msdp_peer *mp, struct prefix_sg *sg,
       }
       /* send an immediate SA update to peers */
       pim_msdp_pkt_sa_tx_one(sa);
-      pim_msdp_sa_upstream_update(sa, NULL /* xg_up */, "local-ref");
     }
     sa->flags &= ~PIM_MSDP_SAF_STALE;
   }
 }
 
-void
-pim_msdp_sa_local_add(struct prefix_sg *sg)
+/* The following criteria must be met to originate an SA from the MSDP
+ * speaker -
+ * 1. KAT must be running i.e. source is active.
+ * 2. We must be RP for the group.
+ * 3. Source must be registrable to the RP (this is where the RFC is vague
+ *    and especially ambiguous in CLOS networks; with anycast RP all sources
+ *    are potentially registrable to all RPs in the domain). We assume #3 is
+ *    satisfied if -
+ *    a. We are also the FHR-DR for the source (OR)
+ *    b. We rxed a pim register (null or data encapsulated) within the last
+ *       (3 * (1.5 * register_suppression_timer))).
+ */
+static bool
+pim_msdp_sa_local_add_ok(struct pim_upstream *up)
 {
-  struct in_addr rp;
-
   if (!(msdp->flags & PIM_MSDPF_ENABLE)) {
-    /* if the feature is not enabled do nothing; we will collect all local
-     * sources whenever it is */
-    return;
+    return false;
   }
 
-  /* check if I am RP for this group. XXX: is this check really needed? */
-  if (!I_am_RP(sg->grp)) {
-    return;
+  if (!up->t_ka_timer) {
+    /* stream is not active */
+    return false;
+  }
+
+  if (!I_am_RP(up->sg.grp)) {
+    /* we are not RP for the group */
+    return false;
+  }
+
+  /* we are the FHR-DR for this stream  or we are RP and have seen registers
+   * from a FHR for this source */
+  if (PIM_UPSTREAM_FLAG_TEST_FHR(up->flags) || up->t_msdp_reg_timer) {
+    return true;
   }
+
+  return false;
+}
+
+static void
+pim_msdp_sa_local_add(struct prefix_sg *sg)
+{
+  struct in_addr rp;
   rp.s_addr = 0;
   pim_msdp_sa_ref(NULL /* mp */, sg, rp);
 }
@@ -454,18 +483,31 @@ pim_msdp_sa_local_del(struct prefix_sg *sg)
 {
   struct pim_msdp_sa *sa;
 
-  if (!(msdp->flags & PIM_MSDPF_ENABLE)) {
-    /* if the feature is not enabled do nothing; we will collect all local
-     * sources whenever it is */
-    return;
-  }
-
   sa = pim_msdp_sa_find(sg);
   if (sa) {
     pim_msdp_sa_deref(sa, PIM_MSDP_SAF_LOCAL);
   }
 }
 
+/* Local SA qualification needs to be re-evaluated when -
+ * 1. KAT is started or stopped
+ * 2. on RP changes
+ * 3. Whenever FHR status changes for a (S,G) - XXX - currently there
+ *    is no clear path to transition an entry out of "MASK_FHR" need
+ *    to discuss this with Donald. May result in some strangeness if the
+ *    FHR is also the RP.
+ * 4. When msdp_reg timer is started or stopped
+ */
+void
+pim_msdp_sa_local_update(struct pim_upstream *up)
+{
+  if (pim_msdp_sa_local_add_ok(up)) {
+    pim_msdp_sa_local_add(&up->sg);
+  } else {
+    pim_msdp_sa_local_del(&up->sg);
+  }
+}
+
 static void
 pim_msdp_sa_local_setup(void)
 {
@@ -473,9 +515,7 @@ pim_msdp_sa_local_setup(void)
   struct listnode *up_node;
 
   for (ALL_LIST_ELEMENTS_RO(pim_upstream_list, up_node, up)) {
-    if (PIM_UPSTREAM_FLAG_TEST_CREATED_BY_UPSTREAM(up->flags)) {
-      pim_msdp_sa_local_add(&up->sg);
-    }
+    pim_msdp_sa_local_update(up);
   }
 }
 
@@ -548,8 +588,6 @@ pim_msdp_up_join_state_changed(struct pim_upstream *xg_up)
   }
 }
 
-/* XXX: Need to maintain SAs per-group to avoid all this unnecessary
- * walking */
 void
 pim_msdp_up_xg_del(struct prefix_sg *sg)
 {