gnrc/nib: consolidate prefix removal code in _nib_offl_remove_prefix()

sys/net/gnrc/network_layer/ipv6/nib/_nib-internal.c

@@ -679,6 +679,38 @@ void _nib_pl_remove(_nib_offl_entry_t *nib_offl)
 #endif  /* CONFIG_GNRC_IPV6_NIB_MULTIHOP_P6C */
 }
 
+void _nib_offl_remove_prefix(_nib_offl_entry_t *pfx)
+{
+    gnrc_netif_t *netif;
+
+    /* remove prefix timer */
+    evtimer_del(&_nib_evtimer, &pfx->pfx_timeout.event);
+
+    /* get interface associated with prefix */
+    netif = gnrc_netif_get_by_pid(_nib_onl_get_if(pfx->next_hop));
+
+    if (netif != NULL) {
+        uint8_t best_match_len = pfx->pfx_len;
+        ipv6_addr_t *best_match = NULL;
+
+        /* remove address associated with prefix */
+        for (int i = 0; i < CONFIG_GNRC_NETIF_IPV6_ADDRS_NUMOF; i++) {
+            if (ipv6_addr_match_prefix(&netif->ipv6.addrs[i],
+                                       &pfx->pfx) >= best_match_len) {
+                best_match_len = pfx->pfx_len;
+                best_match = &netif->ipv6.addrs[i];
+            }
+        }
+        if (best_match != NULL) {
+            gnrc_netif_ipv6_addr_remove_internal(netif,
+                                                 best_match);
+        }
+    }
+
+    /* remove prefix */
+    _nib_pl_remove(pfx);
+}
+
 #if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_MULTIHOP_P6C)
 _nib_abr_entry_t *_nib_abr_add(const ipv6_addr_t *addr)
 {

sys/net/gnrc/network_layer/ipv6/nib/_nib-internal.h

@@ -683,6 +683,16 @@ _nib_offl_entry_t *_nib_pl_add(unsigned iface,
  */
 void _nib_pl_remove(_nib_offl_entry_t *nib_offl);
 
+/**
+ * @brief   Removes a prefix from the prefix list as well as the addresses
+ *          associated with the prefix.
+ *
+ * @param[in,out] nib_offl    An entry.
+ *
+ * Corresponding on-link entry is removed, too.
+ */
+void _nib_offl_remove_prefix(_nib_offl_entry_t *pfx);
+
 #if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_ROUTER) || DOXYGEN
 /**
  * @brief   Creates or gets an existing forwarding table entry by its prefix

sys/net/gnrc/network_layer/ipv6/nib/_nib-router.c

@@ -269,6 +269,24 @@ void _set_rtr_adv(gnrc_netif_t *netif)
     _handle_snd_mc_ra(netif);
 }
 
+void _snd_rtr_advs_drop_pfx(gnrc_netif_t *netif, const ipv6_addr_t *dst,
+                            _nib_offl_entry_t *pfx)
+{
+    gnrc_pktsnip_t *ext_opts = NULL;
+    uint32_t now = evtimer_now_msec();
+
+    DEBUG("nib: broadcasting removal of %s/%u from %u\n",
+          ipv6_addr_to_str(addr_str, &pfx->pfx, sizeof(addr_str)),
+          pfx->pfx_len, netif->pid
+    );
+
+    pfx->pref_until  = now + 10;   /* add some safety margin */
+    pfx->valid_until = now + 10;   /* will be rounded to sec */
+
+    ext_opts = _offl_to_pio(pfx, ext_opts);
+    gnrc_ndp_rtr_adv_send(netif, NULL, dst, false, ext_opts);
+}
+
 static void _snd_ra(gnrc_netif_t *netif, const ipv6_addr_t *dst,
                     bool final, _nib_abr_entry_t *abr)
 {

sys/net/gnrc/network_layer/ipv6/nib/_nib-router.h

@@ -118,6 +118,16 @@ void _set_rtr_adv(gnrc_netif_t *netif);
  */
 void _snd_rtr_advs(gnrc_netif_t *netif, const ipv6_addr_t *dst,
                   bool final);
+/**
+ * @brief   Send router advertisements to remove a prefix
+ *
+ * @param[in] netif The interface to send the router advertisement over.
+ * @param[in] dst   Destination address for the router advertisement.
+ * @param[in] pfx   Off-link entry of the prefix that should be removed.
+ *
+ */
+void _snd_rtr_advs_drop_pfx(gnrc_netif_t *netif, const ipv6_addr_t *dst,
+                            _nib_offl_entry_t *pfx);
 #else  /* CONFIG_GNRC_IPV6_NIB_ROUTER */
 #define _init_iface_router(netif)                       (void)netif
 #define _call_route_info_cb(netif, type, ctx_addr, ctx) (void)netif; \
@@ -130,6 +140,9 @@ void _snd_rtr_advs(gnrc_netif_t *netif, const ipv6_addr_t *dst,
 #define _snd_rtr_advs(netif, dst, final)                (void)netif; \
                                                         (void)dst; \
                                                         (void)final
+#define _snd_rtr_advs_drop_pfx(netif, dst, pfx)         (void)netif; \
+                                                        (void)dst; \
+                                                        (void)pfx;
 #endif /* CONFIG_GNRC_IPV6_NIB_ROUTER */
 
 #ifdef __cplusplus

sys/net/gnrc/network_layer/ipv6/nib/nib.c

@@ -1331,16 +1331,7 @@ static void _handle_pfx_timeout(_nib_offl_entry_t *pfx)
 
     gnrc_netif_acquire(netif);
     if (now >= pfx->valid_until) {
-        evtimer_del(&_nib_evtimer, &pfx->pfx_timeout.event);
+        _nib_offl_remove_prefix(pfx);
-        for (int i = 0; i < CONFIG_GNRC_NETIF_IPV6_ADDRS_NUMOF; i++) {
-            if (ipv6_addr_match_prefix(&netif->ipv6.addrs[i],
-                                       &pfx->pfx) >= pfx->pfx_len) {
-                gnrc_netif_ipv6_addr_remove_internal(netif,
-                                                     &netif->ipv6.addrs[i]);
-            }
-        }
-        pfx->mode &= ~_PL;
-        _nib_offl_clear(pfx);
     }
     else if (now >= pfx->pref_until) {
         for (int i = 0; i < CONFIG_GNRC_NETIF_IPV6_ADDRS_NUMOF; i++) {
@@ -1495,10 +1486,9 @@ static void _remove_prefix(const ipv6_addr_t *pfx, unsigned pfx_len)
         if ((offl->mode & _PL) &&
             (offl->pfx_len == pfx_len) &&
             (ipv6_addr_match_prefix(&offl->pfx, pfx) >= pfx_len)) {
-            _nib_pl_remove(offl);
+            _nib_offl_remove_prefix(offl);
         }
     }
-    return;
 }
 
 #if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_MULTIHOP_P6C)

sys/net/gnrc/network_layer/ipv6/nib/nib_pl.c

@@ -104,17 +104,18 @@ void gnrc_ipv6_nib_pl_del(unsigned iface,
         if ((pfx_len == dst->pfx_len) &&
             ((iface == 0) || (iface == _nib_onl_get_if(dst->next_hop))) &&
             (ipv6_addr_match_prefix(pfx, &dst->pfx) >= pfx_len)) {
-            _nib_pl_remove(dst);
+
-            _nib_release();
+            /* notify downstream nodes about the prefix removal */
 #if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_ROUTER)
             gnrc_netif_t *netif = gnrc_netif_get_by_pid(iface);
 
-            if (netif) {
+            if (netif && (netif->flags & GNRC_NETIF_FLAGS_IPV6_RTR_ADV)) {
-                /* update prefixes down-stream */
+                _snd_rtr_advs_drop_pfx(netif, &ipv6_addr_all_nodes_link_local, dst);
-                _handle_snd_mc_ra(netif);
             }
 #endif
-            return;
+            /* remove the prefix & associated address*/
+            _nib_offl_remove_prefix(dst);
+            break;
         }
     }
     _nib_release();