[PATCH] ndp: Don't send unsolicited router advertisement if we can't, yet

[Stefano Brivio <sbrivio@redhat.com>]

ndp_timer() is called right away on the first epoll_wait() cycle,
when the communication channel to the guest isn't ready yet:

  1.0038: NDP: sending unsolicited RA, next in 264s
  1.0038: tap: failed to send 1 frames of 1

check that it's up before sending it. This effectively delays the
first gratuitous router advertisement, which is probably a good idea
given that we expect the guest to send a router solicitation right
away.

Fixes: 6e1e44293ef9 ("ndp: Send unsolicited Router Advertisements")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 ndp.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/ndp.c b/ndp.c
index 7ee44b2..b458785 100644
--- a/ndp.c
+++ b/ndp.c
@@ -420,9 +420,12 @@ void ndp_timer(const struct ctx *c, const struct timespec *now)
 	interval = min_rtr_adv_interval +
 		random() % (max_rtr_adv_interval - min_rtr_adv_interval);
 
-	info("NDP: sending unsolicited RA, next in %llds", (long long)interval);
+	if (next_ra) {
+		info("NDP: sending unsolicited RA, next in %llds",
+		     (long long)interval);
 
-	ndp_ra(c, &in6addr_ll_all_nodes);
+		ndp_ra(c, &in6addr_ll_all_nodes);
+	}
 
 	next_ra = now->tv_sec + interval;
 }
-- 
@@ -420,9 +420,12 @@ void ndp_timer(const struct ctx *c, const struct timespec *now)
 	interval = min_rtr_adv_interval +
 		random() % (max_rtr_adv_interval - min_rtr_adv_interval);
 
-	info("NDP: sending unsolicited RA, next in %llds", (long long)interval);
+	if (next_ra) {
+		info("NDP: sending unsolicited RA, next in %llds",
+		     (long long)interval);
 
-	ndp_ra(c, &in6addr_ll_all_nodes);
+		ndp_ra(c, &in6addr_ll_all_nodes);
+	}
 
 	next_ra = now->tv_sec + interval;
 }
-- 
2.43.0