bgpd: Stop LLGR timer when the connection is established

When the connection goes up, the timer is not stopped and if we have a
subsequent GR event we have an old timer which is not as we expect.

Before:
```
spine1-debian-11# sh ip bgp 192.168.100.1/32
BGP routing table entry for 192.168.100.1/32, version 95
Paths: (1 available, best #1, table default, mark routes to be retained for a longer time. Requires support for Long-lived BGP Graceful Restart)
  Not advertised to any peer
  65001 47583, (stale)
    192.168.0.1 from 192.168.0.1 (100.100.200.100)
      Origin incomplete, valid, external, best (First path received)
      Community: llgr-stale
      Last update: Mon Mar 28 08:27:53 2022
      Time until Long-lived stale route deleted: 23 <<<<<<<<<<<<

spine1-debian-11# sh ip bgp 192.168.100.1/32
BGP routing table entry for 192.168.100.1/32, version 103
Paths: (1 available, best #1, table default)
  Advertised to non peer-group peers:
  192.168.0.1
  65001 47583
    192.168.0.1 from 192.168.0.1 (100.100.200.100)
      Origin incomplete, valid, external, best (First path received)
      Last update: Mon Mar 28 08:43:29 2022

spine1-debian-11# sh ip bgp 192.168.100.1/32
BGP routing table entry for 192.168.100.1/32, version 103
Paths: (1 available, best #1, table default, mark routes to be retained for a longer time. Requires support for Long-lived BGP Graceful Restart)
  Not advertised to any peer
  65001 47583, (stale)
    192.168.0.1 from 192.168.0.1 (100.100.200.100)
      Origin incomplete, valid, external, best (First path received)
      Community: llgr-stale
      Last update: Mon Mar 28 08:43:30 2022
      Time until Long-lived stale route deleted: 17 <<<<<<<<<<<<<<<
```

After:
```
spine1-debian-11# sh ip bgp 192.168.100.1/32
BGP routing table entry for 192.168.100.1/32, version 79
Paths: (1 available, best #1, table default, mark routes to be retained for a longer time. Requires support for Long-lived BGP Graceful Restart)
  Not advertised to any peer
  65001 47583, (stale)
    192.168.0.1 from 192.168.0.1 (0.0.0.0)
      Origin incomplete, valid, external, best (First path received)
      Community: llgr-stale
      Last update: Mon Mar 28 09:05:18 2022
      Time until Long-lived stale route deleted: 24 <<<<<<<<<<<<<<<

spine1-debian-11# sh ip bgp 192.168.100.1/32
BGP routing table entry for 192.168.100.1/32, version 87
Paths: (1 available, best #1, table default)
  Advertised to non peer-group peers:
  192.168.0.1
  65001 47583
    192.168.0.1 from 192.168.0.1 (100.100.200.100)
      Origin incomplete, valid, external, best (First path received)
      Last update: Mon Mar 28 09:05:25 2022

spine1-debian-11# sh ip bgp 192.168.100.1/32
BGP routing table entry for 192.168.100.1/32, version 87
Paths: (1 available, best #1, table default, mark routes to be retained for a longer time. Requires support for Long-lived BGP Graceful Restart)
  Not advertised to any peer
  65001 47583, (stale)
    192.168.0.1 from 192.168.0.1 (100.100.200.100)
      Origin incomplete, valid, external, best (First path received)
      Community: llgr-stale
      Last update: Mon Mar 28 09:05:29 2022
      Time until Long-lived stale route deleted: 29 <<<<<<<<<<<<<<
```

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
(cherry picked from commit 0d4532cd828b0538bf759ad2401e3cc1b7f7e135)

diff --git a/bgpd/bgp_fsm.c b/bgpd/bgp_fsm.c
index 672fa4512ae6df852e0d8e8954d8715cee8b6f5d..3ca4aa51358134d413e7fd7b7f02564fb5ff3301 100644 (file)
--- a/bgpd/bgp_fsm.c
+++ b/bgpd/bgp_fsm.c
@@ -2225,8 +2225,18 @@ static int bgp_establish(struct peer *peer)
 
        peer->uptime = bgp_clock();
 
-       /* Send route-refresh when ORF is enabled */
+       /* Send route-refresh when ORF is enabled.
+        * Stop Long-lived Graceful Restart timers.
+        */
        FOREACH_AFI_SAFI (afi, safi) {
+               if (peer->t_llgr_stale[afi][safi]) {
+                       BGP_TIMER_OFF(peer->t_llgr_stale[afi][safi]);
+                       if (bgp_debug_neighbor_events(peer))
+                               zlog_debug(
+                                       "%s Long-lived stale timer stopped for afi/safi: %d/%d",
+                                       peer->host, afi, safi);
+               }
+
                if (CHECK_FLAG(peer->af_cap[afi][safi],
                               PEER_CAP_ORF_PREFIX_SM_ADV)) {
                        if (CHECK_FLAG(peer->af_cap[afi][safi],