From 23727917b234203bd98b874d7200e31b844685bd Mon Sep 17 00:00:00 2001
From: Beniamino Galvani <bgalvani@redhat.com>
Date: Fri, 1 Sep 2023 16:40:29 +0200
Subject: [PATCH] n-acd: use separate seed state for each probe of the same acd

Currently, all the probes of an acd instance share the same seed
state. This means that the state is updated by all the probes, and as
a consequence they get different jitters for the wait timeouts;
therefore the order in which addresses become available (and are
configured on the interface) is not deterministic.

Keep a separate seed state for each probe, initialized from the acd
seed. This ensures that all the probes use the same timeouts when
sending probe requests, and that in case of no collision, addresses
are available in the order of probe start.

n-acd pull request: https://github.com/nettools/n-acd/pull/10
---
 src/n-acd/src/n-acd-private.h | 1 +
 src/n-acd/src/n-acd-probe.c   | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/n-acd/src/n-acd-private.h b/src/n-acd/src/n-acd-private.h
index 4583c018e2..db28b1a560 100644
--- a/src/n-acd/src/n-acd-private.h
+++ b/src/n-acd/src/n-acd-private.h
@@ -105,6 +105,7 @@ struct NAcdProbe {
         void *userdata;
 
         /* state */
+        unsigned int seed;
         unsigned int state;
         unsigned int n_iteration;
         unsigned int defend;
diff --git a/src/n-acd/src/n-acd-probe.c b/src/n-acd/src/n-acd-probe.c
index c1ed59ae9e..d32e0103b4 100644
--- a/src/n-acd/src/n-acd-probe.c
+++ b/src/n-acd/src/n-acd-probe.c
@@ -172,7 +172,7 @@ static void n_acd_probe_schedule(NAcdProbe *probe, uint64_t n_timeout, unsigned
         if (n_jitter) {
                 uint64_t random;
 
-                random = ((uint64_t)rand_r(&probe->acd->seed) << 32) | (uint64_t)rand_r(&probe->acd->seed);
+                random = ((uint64_t)rand_r(&probe->seed) << 32) | (uint64_t)rand_r(&probe->seed);
                 n_time += random % n_jitter;
         }
 
@@ -283,6 +283,7 @@ int n_acd_probe_new(NAcdProbe **probep, NAcd *acd, NAcdProbeConfig *config) {
         *probe = (NAcdProbe)N_ACD_PROBE_NULL(*probe);
         probe->acd = n_acd_ref(acd);
         probe->ip = config->ip;
+        probe->seed = acd->seed;
 
         /*
          * We use the provided timeout-length as multiplier for all our