ipcpd: Only forward new LSAs of the LSDB

This will add a sequence number to the Link State Advertisements so
that upon receiving a LSA we can check if we need to forward the LSA
or not. If we already have the LSA with the received seqno in the LSDB
we do not forward it. This allows for setting up a management network
that has loops since the spanning tree upon which the LSAs are sent is
pruned on every hop.

Signed-off-by: Sander Vrijders <sander.vrijders@ugent.be>
Signed-off-by: Dimitri Staessens <dimitri.staessens@ugent.be>

1 files changed, 36 insertions, 17 deletions

diff --git a/src/ipcpd/normal/pol/link_state.c b/src/ipcpd/normal/pol/link_state.c
index ac893432..8e5d3807 100644
--- a/src/ipcpd/normal/pol/link_state.c
+++ b/src/ipcpd/normal/pol/link_state.c
@@ -53,16 +53,21 @@
 #define RECALC_TIME    4
 #define LS_UPDATE_TIME 15
 #define LS_TIMEO       60
-#define LS_ENTRY_SIZE  78
+#define LS_ENTRY_SIZE  104
 #define LSDB           "lsdb"
 
 #ifndef CLOCK_REALTIME_COARSE
 #define CLOCK_REALTIME_COARSE CLOCK_REALTIME
 #endif
 
+#define LSA_NEW     0
+#define LSA_UPDATED 1
+#define LSA_OLD     2
+
 struct lsa {
         uint64_t d_addr;
         uint64_t s_addr;
+        uint64_t seqno;
 } __attribute__((packed));
 
 struct routing_i {
@@ -82,6 +87,8 @@ struct adjacency {
         uint64_t         dst;
         uint64_t         src;
 
+        uint64_t         seqno;
+
         time_t           stamp;
 };
 
@@ -138,6 +145,7 @@ static int str_adj(struct adjacency * adj,
         char        tmbuf[64];
         char        srcbuf[64];
         char        dstbuf[64];
+        char        seqnobuf[64];
         struct tm * tm;
 
         if (len < LS_ENTRY_SIZE)
@@ -148,9 +156,10 @@ static int str_adj(struct adjacency * adj,
 
         sprintf(srcbuf, "%" PRIu64, adj->src);
         sprintf(dstbuf, "%" PRIu64, adj->dst);
+        sprintf(seqnobuf, "%" PRIu64, adj->seqno);
 
-        sprintf(buf, "src: %20s\ndst: %20s\nupd: %20s\n",
-                srcbuf, dstbuf, tmbuf);
+        sprintf(buf, "src: %20s\ndst: %20s\nseqno: %18s\nupd: %20s\n",
+                srcbuf, dstbuf, seqnobuf, tmbuf);
 
         return LS_ENTRY_SIZE;
 }
@@ -386,11 +395,13 @@ static void set_pff_modified(void)
 
 static int lsdb_add_link(uint64_t    src,
                          uint64_t    dst,
+                         uint64_t    seqno,
                          qosspec_t * qs)
 {
         struct list_head * p;
         struct adjacency * adj;
         struct timespec    now;
+        int                ret;
 
         clock_gettime(CLOCK_REALTIME_COARSE, &now);
 
@@ -399,9 +410,11 @@ static int lsdb_add_link(uint64_t    src,
         list_for_each(p, &ls.db) {
                 struct adjacency * a = list_entry(p, struct adjacency, next);
                 if (a->dst == dst && a->src == src) {
+                        ret = (a->seqno <= seqno ? LSA_OLD : LSA_UPDATED);
                         a->stamp = now.tv_sec;
+                        a->seqno = seqno;
                         pthread_rwlock_unlock(&ls.db_lock);
-                        return 0;
+                        return ret;
                 }
 
                 if (a->dst > dst || (a->dst == dst && a->src > src))
@@ -416,6 +429,7 @@ static int lsdb_add_link(uint64_t    src,
 
         adj->dst   = dst;
         adj->src   = src;
+        adj->seqno = seqno;
         adj->stamp = now.tv_sec;
 
         list_add_tail(&adj->next, p);
@@ -429,7 +443,7 @@ static int lsdb_add_link(uint64_t    src,
 
         set_pff_modified();
 
-        return 0;
+        return LSA_NEW;
 }
 
 static int lsdb_del_link(uint64_t src,
@@ -539,13 +553,15 @@ static void * periodic_recalc_pff(void * o)
 }
 
 static void send_lsm(uint64_t src,
-                     uint64_t dst)
+                     uint64_t dst,
+                     uint64_t seqno)
 {
         struct lsa         lsm;
         struct list_head * p;
 
         lsm.d_addr = hton64(dst);
         lsm.s_addr = hton64(src);
+        lsm.seqno  = hton64(seqno);
 
         list_for_each(p, &ls.nbs) {
                 struct nb * nb = list_entry(p, struct nb, next);
@@ -576,8 +592,9 @@ static void lsdb_replicate(int fd)
                         break;
                 }
 
-                cpy->dst = adj->dst;
-                cpy->src = adj->src;
+                cpy->dst   = adj->dst;
+                cpy->src   = adj->src;
+                cpy->seqno = adj->seqno;
 
                 list_add_tail(&cpy->next, &copy);
         }
@@ -590,6 +607,7 @@ static void lsdb_replicate(int fd)
                 adj = list_entry(p, struct adjacency, next);
                 lsm.d_addr = hton64(adj->dst);
                 lsm.s_addr = hton64(adj->src);
+                lsm.seqno  = hton64(adj->seqno);
                 list_del(&adj->next);
                 free(adj);
                 flow_write(fd, &lsm, sizeof(lsm));
@@ -627,7 +645,8 @@ static void * lsupdate(void * o)
                         }
 
                         if (adj->src == ipcpi.dt_addr) {
-                                send_lsm(adj->src, adj->dst);
+                                adj->seqno++;
+                                send_lsm(adj->src, adj->dst, adj->seqno);
                                 adj->stamp = now.tv_sec;
                         }
                 }
@@ -716,11 +735,11 @@ static void * lsreader(void * o)
 
                         msg = (struct lsa *) buf;
 
-                        lsdb_add_link(ntoh64(msg->s_addr),
-                                      ntoh64(msg->d_addr),
-                                      &qs);
-
-                        forward_lsm(buf, len, fd);
+                        if (lsdb_add_link(ntoh64(msg->s_addr),
+                                          ntoh64(msg->d_addr),
+                                          ntoh64(msg->seqno),
+                                          &qs) != LSA_OLD)
+                                forward_lsm(buf, len, fd);
                 }
         }
 
@@ -767,10 +786,10 @@ static void handle_event(void *       self,
                 if (lsdb_add_nb(c->conn_info.addr, c->flow_info.fd, NB_DT))
                         log_dbg("Failed to add neighbor to LSDB.");
 
-                if (lsdb_add_link(ipcpi.dt_addr, c->conn_info.addr, &qs))
-                        log_dbg("Failed to add adjacency to LSDB.");
+                if (lsdb_add_link(ipcpi.dt_addr, c->conn_info.addr, 0, &qs))
+                        log_dbg("Failed to add new adjacency to LSDB.");
 
-                send_lsm(ipcpi.dt_addr, c->conn_info.addr);
+                send_lsm(ipcpi.dt_addr, c->conn_info.addr, 0);
 
                 break;
         case NOTIFY_DT_CONN_DEL: