batman-adv: substitute tt_poss_change with a per-tt_entry flag
tt_poss_change is a node-wide flag which tells whether the node is in a roaming
state (a client recently moved to/away from it) in order to let it apply special
re-routing rules. However this flag does not give a clear idea of the current
state because it is not possible to understand *which client* is actually
involved in the roaming. For this reason a better approach has been chosen:
instead of using a node-wide variable, the roaming state is now given by a
per-tt_entry ROAM flag which, in case of packet coming through the node, tells
the node whether the real destination is in roaming state or not.
With this flag change, batadv_check_unicast_ttvn() has also been rearranged in
order to better fit the new re-routing logic and to be much more readable.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 32aa4d4..78d6572 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -711,12 +711,6 @@
BATADV_TT_CLIENT_ROAM,
atomic_read(&orig_node->last_ttvn) + 1);
- /* Roaming phase starts: I have new information but the ttvn has not
- * been incremented yet. This flag will make me check all the incoming
- * packets for the correct destination.
- */
- bat_priv->tt.poss_change = true;
-
batadv_orig_node_free_ref(orig_node);
out:
/* returning NET_RX_DROP will make the caller function kfree the skb */
@@ -899,14 +893,67 @@
return ret;
}
+/**
+ * batadv_reroute_unicast_packet - update the unicast header for re-routing
+ * @bat_priv: the bat priv with all the soft interface information
+ * @unicast_packet: the unicast header to be updated
+ * @dst_addr: the payload destination
+ *
+ * Search the translation table for dst_addr and update the unicast header with
+ * the new corresponding information (originator address where the destination
+ * client currently is and its known TTVN)
+ *
+ * Returns true if the packet header has been updated, false otherwise
+ */
+static bool
+batadv_reroute_unicast_packet(struct batadv_priv *bat_priv,
+ struct batadv_unicast_packet *unicast_packet,
+ uint8_t *dst_addr)
+{
+ struct batadv_orig_node *orig_node = NULL;
+ struct batadv_hard_iface *primary_if = NULL;
+ bool ret = false;
+ uint8_t *orig_addr, orig_ttvn;
+
+ if (batadv_is_my_client(bat_priv, dst_addr)) {
+ primary_if = batadv_primary_if_get_selected(bat_priv);
+ if (!primary_if)
+ goto out;
+ orig_addr = primary_if->net_dev->dev_addr;
+ orig_ttvn = (uint8_t)atomic_read(&bat_priv->tt.vn);
+ } else {
+ orig_node = batadv_transtable_search(bat_priv, NULL, dst_addr);
+ if (!orig_node)
+ goto out;
+
+ if (batadv_compare_eth(orig_node->orig, unicast_packet->dest))
+ goto out;
+
+ orig_addr = orig_node->orig;
+ orig_ttvn = (uint8_t)atomic_read(&orig_node->last_ttvn);
+ }
+
+ /* update the packet header */
+ memcpy(unicast_packet->dest, orig_addr, ETH_ALEN);
+ unicast_packet->ttvn = orig_ttvn;
+
+ ret = true;
+out:
+ if (primary_if)
+ batadv_hardif_free_ref(primary_if);
+ if (orig_node)
+ batadv_orig_node_free_ref(orig_node);
+
+ return ret;
+}
+
static int batadv_check_unicast_ttvn(struct batadv_priv *bat_priv,
struct sk_buff *skb) {
- uint8_t curr_ttvn;
+ uint8_t curr_ttvn, old_ttvn;
struct batadv_orig_node *orig_node;
struct ethhdr *ethhdr;
struct batadv_hard_iface *primary_if;
struct batadv_unicast_packet *unicast_packet;
- bool tt_poss_change;
int is_old_ttvn;
/* check if there is enough data before accessing it */
@@ -918,65 +965,89 @@
return 0;
unicast_packet = (struct batadv_unicast_packet *)skb->data;
+ ethhdr = (struct ethhdr *)(skb->data + sizeof(*unicast_packet));
- if (batadv_is_my_mac(unicast_packet->dest)) {
- tt_poss_change = bat_priv->tt.poss_change;
- curr_ttvn = (uint8_t)atomic_read(&bat_priv->tt.vn);
- } else {
+ /* check if the destination client was served by this node and it is now
+ * roaming. In this case, it means that the node has got a ROAM_ADV
+ * message and that it knows the new destination in the mesh to re-route
+ * the packet to
+ */
+ if (batadv_tt_local_client_is_roaming(bat_priv, ethhdr->h_dest)) {
+ if (batadv_reroute_unicast_packet(bat_priv, unicast_packet,
+ ethhdr->h_dest))
+ net_ratelimited_function(batadv_dbg, BATADV_DBG_TT,
+ bat_priv,
+ "Rerouting unicast packet to %pM (dst=%pM): Local Roaming\n",
+ unicast_packet->dest,
+ ethhdr->h_dest);
+ /* at this point the mesh destination should have been
+ * substituted with the originator address found in the global
+ * table. If not, let the packet go untouched anyway because
+ * there is nothing the node can do
+ */
+ return 1;
+ }
+
+ /* retrieve the TTVN known by this node for the packet destination. This
+ * value is used later to check if the node which sent (or re-routed
+ * last time) the packet had an updated information or not
+ */
+ curr_ttvn = (uint8_t)atomic_read(&bat_priv->tt.vn);
+ if (!batadv_is_my_mac(unicast_packet->dest)) {
orig_node = batadv_orig_hash_find(bat_priv,
unicast_packet->dest);
-
+ /* if it is not possible to find the orig_node representing the
+ * destination, the packet can immediately be dropped as it will
+ * not be possible to deliver it
+ */
if (!orig_node)
return 0;
curr_ttvn = (uint8_t)atomic_read(&orig_node->last_ttvn);
- tt_poss_change = orig_node->tt_poss_change;
batadv_orig_node_free_ref(orig_node);
}
- /* Check whether I have to reroute the packet */
+ /* check if the TTVN contained in the packet is fresher than what the
+ * node knows
+ */
is_old_ttvn = batadv_seq_before(unicast_packet->ttvn, curr_ttvn);
- if (is_old_ttvn || tt_poss_change) {
- /* check if there is enough data before accessing it */
- if (pskb_may_pull(skb, sizeof(struct batadv_unicast_packet) +
- ETH_HLEN) < 0)
- return 0;
+ if (!is_old_ttvn)
+ return 1;
- ethhdr = (struct ethhdr *)(skb->data + sizeof(*unicast_packet));
-
- /* we don't have an updated route for this client, so we should
- * not try to reroute the packet!!
- */
- if (batadv_tt_global_client_is_roaming(bat_priv,
- ethhdr->h_dest))
- return 1;
-
- orig_node = batadv_transtable_search(bat_priv, NULL,
- ethhdr->h_dest);
-
- if (!orig_node) {
- if (!batadv_is_my_client(bat_priv, ethhdr->h_dest))
- return 0;
- primary_if = batadv_primary_if_get_selected(bat_priv);
- if (!primary_if)
- return 0;
- memcpy(unicast_packet->dest,
- primary_if->net_dev->dev_addr, ETH_ALEN);
- batadv_hardif_free_ref(primary_if);
- } else {
- memcpy(unicast_packet->dest, orig_node->orig,
- ETH_ALEN);
- curr_ttvn = (uint8_t)atomic_read(&orig_node->last_ttvn);
- batadv_orig_node_free_ref(orig_node);
- }
-
+ old_ttvn = unicast_packet->ttvn;
+ /* the packet was forged based on outdated network information. Its
+ * destination can possibly be updated and forwarded towards the new
+ * target host
+ */
+ if (batadv_reroute_unicast_packet(bat_priv, unicast_packet,
+ ethhdr->h_dest)) {
net_ratelimited_function(batadv_dbg, BATADV_DBG_TT, bat_priv,
- "TTVN mismatch (old_ttvn %u new_ttvn %u)! Rerouting unicast packet (for %pM) to %pM\n",
- unicast_packet->ttvn, curr_ttvn,
- ethhdr->h_dest, unicast_packet->dest);
-
- unicast_packet->ttvn = curr_ttvn;
+ "Rerouting unicast packet to %pM (dst=%pM): TTVN mismatch old_ttvn=%u new_ttvn=%u\n",
+ unicast_packet->dest, ethhdr->h_dest,
+ old_ttvn, curr_ttvn);
+ return 1;
}
+
+ /* the packet has not been re-routed: either the destination is
+ * currently served by this node or there is no destination at all and
+ * it is possible to drop the packet
+ */
+ if (!batadv_is_my_client(bat_priv, ethhdr->h_dest))
+ return 0;
+
+ /* update the header in order to let the packet be delivered to this
+ * node's soft interface
+ */
+ primary_if = batadv_primary_if_get_selected(bat_priv);
+ if (!primary_if)
+ return 0;
+
+ memcpy(unicast_packet->dest, primary_if->net_dev->dev_addr, ETH_ALEN);
+
+ batadv_hardif_free_ref(primary_if);
+
+ unicast_packet->ttvn = curr_ttvn;
+
return 1;
}