platform: make "now" timestamp an in/out parameter to nmp_utils_lifetime_get()

nmp_utils_lifetime_get() calculates the lifetime of addresses,
and it bases the result on a "now" timestamp.

If you have two addresses and calculate their expiry, then we want to
base it on top of the same "now" timestamp, meaning, we should
only call nm_utils_get_monotonic_timestamp_sec() once. This is also a
performance optimization. But much more importantly, when we make a
comparison at a certain moment, we need that all sides have the same
understanding of the current timestamp.

But nmp_utils_lifetime_get() does not always require the now timestamp.
And the caller doesn't know, whether it will need it (short of knowing
how nmp_utils_lifetime_get() is implemented). So, make the now parameter
an in/out argument. If we pass in an already valid now timestamp, use
that. Otherwise, fetch the current time and also return it.

src/core/ndisc/nm-ndisc.c

@@ -996,6 +996,7 @@ nm_ndisc_set_config(NMNDisc *ndisc, const NML3ConfigData *l3cd)
     const NMPObject       *obj;
     guint                  len;
     guint                  i;
+    gint32                 fake_now = NM_NDISC_EXPIRY_BASE_TIMESTAMP / 1000;
 
     nm_assert(NM_IS_NDISC(ndisc));
     nm_assert(nm_ndisc_get_node_type(ndisc) == NM_NDISC_NODE_TYPE_ROUTER);
@@ -1018,7 +1019,7 @@ nm_ndisc_set_config(NMNDisc *ndisc, const NML3ConfigData *l3cd)
         lifetime = nmp_utils_lifetime_get(addr->timestamp,
                                           addr->lifetime,
                                           addr->preferred,
-                                          NM_NDISC_EXPIRY_BASE_TIMESTAMP / 1000,
+                                          &fake_now,
                                           &preferred);
         if (!lifetime)
             continue;

src/libnm-platform/nm-platform-utils.c

@@ -2132,12 +2132,15 @@ guint32
 nmp_utils_lifetime_get(guint32  timestamp,
                        guint32  lifetime,
                        guint32  preferred,
-                       gint32   now,
+                       gint32  *cached_now,
                        guint32 *out_preferred)
 {
-    guint32 t_lifetime, t_preferred;
+    guint32 t_lifetime;
+    guint32 t_preferred;
+    gint32  now;
 
-    nm_assert(now >= 0);
+    nm_assert(cached_now);
+    nm_assert(*cached_now >= 0);
 
     if (timestamp == 0 && lifetime == 0) {
         /* We treat lifetime==0 && timestamp==0 addresses as permanent addresses to allow easy
@@ -2150,8 +2153,7 @@ nmp_utils_lifetime_get(guint32  timestamp,
         return NM_PLATFORM_LIFETIME_PERMANENT;
     }
 
-    if (now <= 0)
+    now = nm_utils_get_monotonic_timestamp_sec_cached(cached_now);
-        now = nm_utils_get_monotonic_timestamp_sec();
 
     t_lifetime = nmp_utils_lifetime_rebase_relative_time_on_now(timestamp, lifetime, now);
     if (!t_lifetime) {

src/libnm-platform/nm-platform-utils.h

@@ -86,7 +86,7 @@ nmp_utils_lifetime_rebase_relative_time_on_now(guint32 timestamp, guint32 durati
 guint32 nmp_utils_lifetime_get(guint32  timestamp,
                                guint32  lifetime,
                                guint32  preferred,
-                               gint32   now,
+                               gint32  *cached_now,
                                guint32 *out_preferred);
 
 int nmp_utils_modprobe(GError **error, gboolean suppress_error_logging, const char *arg1, ...)

src/libnm-platform/nm-platform.c

@@ -3696,7 +3696,7 @@ static gboolean
 _addr_array_clean_expired(int          addr_family,
                           int          ifindex,
                           GPtrArray   *array,
-                          guint32      now,
+                          gint32      *cached_now,
                           GHashTable **idx)
 {
     guint    i;
@@ -3704,7 +3704,8 @@ _addr_array_clean_expired(int          addr_family,
 
     nm_assert_addr_family(addr_family);
     nm_assert(ifindex > 0);
-    nm_assert(now > 0);
+    nm_assert(cached_now);
+    nm_assert(*cached_now >= 0);
 
     if (!array)
         return FALSE;
@@ -3738,7 +3739,7 @@ _addr_array_clean_expired(int          addr_family,
             goto clear_and_next;
         }
 
-        if (!nmp_utils_lifetime_get(a->timestamp, a->lifetime, a->preferred, now, NULL))
+        if (!nmp_utils_lifetime_get(a->timestamp, a->lifetime, a->preferred, cached_now, NULL))
             goto clear_and_next;
 
         if (G_UNLIKELY(!*idx)) {
@@ -3981,7 +3982,7 @@ nm_platform_ip_address_sync(NMPlatform *self,
                             GPtrArray  *known_addresses,
                             GPtrArray  *addresses_prune)
 {
-    const gint32                   now     = nm_utils_get_monotonic_timestamp_sec();
+    gint32                         now     = 0;
     const int                      IS_IPv4 = NM_IS_IPv4(addr_family);
     NMPLookup                      lookup;
     const gboolean                 EXTRA_LOGGING       = FALSE;
@@ -4043,7 +4044,7 @@ nm_platform_ip_address_sync(NMPlatform *self,
     if (!_addr_array_clean_expired(addr_family,
                                    ifindex,
                                    known_addresses,
-                                   now,
+                                   &now,
                                    &known_addresses_idx))
         known_addresses = NULL;
 
@@ -4328,7 +4329,7 @@ next_plat:;
         lifetime = nmp_utils_lifetime_get(known_address->ax.timestamp,
                                           known_address->ax.lifetime,
                                           known_address->ax.preferred,
-                                          now,
+                                          &now,
                                           &preferred);
         nm_assert(lifetime > 0);