1 files changed, 179 insertions, 59 deletions

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index 24aee561f3d8..8b25b52a4764 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -20,15 +20,22 @@
  */
 
 #include "main.h"
+#include "bat_sysfs.h"
 #include "gateway_client.h"
 #include "gateway_common.h"
 #include "hard-interface.h"
 #include "originator.h"
+#include "routing.h"
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/udp.h>
 #include <linux/if_vlan.h>
 
+/* This is the offset of the options field in a dhcp packet starting at
+ * the beginning of the dhcp header */
+#define DHCP_OPTIONS_OFFSET 240
+#define DHCP_REQUEST 3
+
 static void gw_node_free_ref(struct gw_node *gw_node)
 {
         if (atomic_dec_and_test(&gw_node->refcount))
@@ -97,40 +104,19 @@ static void gw_select(struct bat_priv *bat_priv, struct gw_node *new_gw_node)
 
 void gw_deselect(struct bat_priv *bat_priv)
 {
-        gw_select(bat_priv, NULL);
+        atomic_set(&bat_priv->gw_reselect, 1);
 }
 
-void gw_election(struct bat_priv *bat_priv)
+static struct gw_node *gw_get_best_gw_node(struct bat_priv *bat_priv)
 {
-        struct hlist_node *node;
-        struct gw_node *gw_node, *curr_gw = NULL, *curr_gw_tmp = NULL;
         struct neigh_node *router;
-        uint8_t max_tq = 0;
+        struct hlist_node *node;
+        struct gw_node *gw_node, *curr_gw = NULL;
         uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
+        uint8_t max_tq = 0;
         int down, up;
 
-        /**
-         * The batman daemon checks here if we already passed a full originator
-         * cycle in order to make sure we don't choose the first gateway we
-         * hear about. This check is based on the daemon's uptime which we
-         * don't have.
-         **/
-        if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT)
-                return;
-
-        curr_gw = gw_get_selected_gw_node(bat_priv);
-        if (curr_gw)
-                goto out;
-
         rcu_read_lock();
-        if (hlist_empty(&bat_priv->gw_list)) {
-                bat_dbg(DBG_BATMAN, bat_priv,
-                        "Removing selected gateway - "
-                        "no gateway in range\n");
-                gw_deselect(bat_priv);
-                goto unlock;
-        }
-
         hlist_for_each_entry_rcu(gw_node, node, &bat_priv->gw_list, list) {
                 if (gw_node->deleted)
                         continue;
@@ -139,6 +125,9 @@ void gw_election(struct bat_priv *bat_priv)
                 if (!router)
                         continue;
 
+                if (!atomic_inc_not_zero(&gw_node->refcount))
+                        goto next;
+
                 switch (atomic_read(&bat_priv->gw_sel_class)) {
                 case 1: /* fast connection */
                         gw_bandwidth_to_kbit(gw_node->orig_node->gw_flags,
@@ -151,8 +140,12 @@ void gw_election(struct bat_priv *bat_priv)
 
                         if ((tmp_gw_factor > max_gw_factor) ||
                             ((tmp_gw_factor == max_gw_factor) &&
-                             (router->tq_avg > max_tq)))
-                                curr_gw_tmp = gw_node;
+                             (router->tq_avg > max_tq))) {
+                                if (curr_gw)
+                                        gw_node_free_ref(curr_gw);
+                                curr_gw = gw_node;
+                                atomic_inc(&curr_gw->refcount);
+                        }
                         break;
 
                 default: /**
@@ -163,8 +156,12 @@ void gw_election(struct bat_priv *bat_priv)
                           *     soon as a better gateway appears which has
                           *     $routing_class more tq points)
                           **/
-                        if (router->tq_avg > max_tq)
-                                curr_gw_tmp = gw_node;
+                        if (router->tq_avg > max_tq) {
+                                if (curr_gw)
+                                        gw_node_free_ref(curr_gw);
+                                curr_gw = gw_node;
+                                atomic_inc(&curr_gw->refcount);
+                        }
                         break;
                 }
 
@@ -174,42 +171,81 @@ void gw_election(struct bat_priv *bat_priv)
                 if (tmp_gw_factor > max_gw_factor)
                         max_gw_factor = tmp_gw_factor;
 
+                gw_node_free_ref(gw_node);
+
+next:
                 neigh_node_free_ref(router);
         }
+        rcu_read_unlock();
 
-        if (curr_gw != curr_gw_tmp) {
-                router = orig_node_get_router(curr_gw_tmp->orig_node);
-                if (!router)
-                        goto unlock;
+        return curr_gw;
+}
 
-                if ((curr_gw) && (!curr_gw_tmp))
-                        bat_dbg(DBG_BATMAN, bat_priv,
-                                "Removing selected gateway - "
-                                "no gateway in range\n");
-                else if ((!curr_gw) && (curr_gw_tmp))
-                        bat_dbg(DBG_BATMAN, bat_priv,
-                                "Adding route to gateway %pM "
-                                "(gw_flags: %i, tq: %i)\n",
-                                curr_gw_tmp->orig_node->orig,
-                                curr_gw_tmp->orig_node->gw_flags,
-                                router->tq_avg);
-                else
-                        bat_dbg(DBG_BATMAN, bat_priv,
-                                "Changing route to gateway %pM "
-                                "(gw_flags: %i, tq: %i)\n",
-                                curr_gw_tmp->orig_node->orig,
-                                curr_gw_tmp->orig_node->gw_flags,
-                                router->tq_avg);
+void gw_election(struct bat_priv *bat_priv)
+{
+        struct gw_node *curr_gw = NULL, *next_gw = NULL;
+        struct neigh_node *router = NULL;
+        char gw_addr[18] = { '\0' };
 
-                neigh_node_free_ref(router);
-                gw_select(bat_priv, curr_gw_tmp);
+        /**
+         * The batman daemon checks here if we already passed a full originator
+         * cycle in order to make sure we don't choose the first gateway we
+         * hear about. This check is based on the daemon's uptime which we
+         * don't have.
+         **/
+        if (atomic_read(&bat_priv->gw_mode) != GW_MODE_CLIENT)
+                goto out;
+
+        if (!atomic_dec_not_zero(&bat_priv->gw_reselect))
+                goto out;
+
+        curr_gw = gw_get_selected_gw_node(bat_priv);
+
+        next_gw = gw_get_best_gw_node(bat_priv);
+
+        if (curr_gw == next_gw)
+                goto out;
+
+        if (next_gw) {
+                sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
+
+                router = orig_node_get_router(next_gw->orig_node);
+                if (!router) {
+                        gw_deselect(bat_priv);
+                        goto out;
+                }
         }
 
-unlock:
-        rcu_read_unlock();
+        if ((curr_gw) && (!next_gw)) {
+                bat_dbg(DBG_BATMAN, bat_priv,
+                        "Removing selected gateway - no gateway in range\n");
+                throw_uevent(bat_priv, UEV_GW, UEV_DEL, NULL);
+        } else if ((!curr_gw) && (next_gw)) {
+                bat_dbg(DBG_BATMAN, bat_priv,
+                        "Adding route to gateway %pM (gw_flags: %i, tq: %i)\n",
+                        next_gw->orig_node->orig,
+                        next_gw->orig_node->gw_flags,
+                        router->tq_avg);
+                throw_uevent(bat_priv, UEV_GW, UEV_ADD, gw_addr);
+        } else {
+                bat_dbg(DBG_BATMAN, bat_priv,
+                        "Changing route to gateway %pM "
+                        "(gw_flags: %i, tq: %i)\n",
+                        next_gw->orig_node->orig,
+                        next_gw->orig_node->gw_flags,
+                        router->tq_avg);
+                throw_uevent(bat_priv, UEV_GW, UEV_CHANGE, gw_addr);
+        }
+
+        gw_select(bat_priv, next_gw);
+
 out:
         if (curr_gw)
                 gw_node_free_ref(curr_gw);
+        if (next_gw)
+                gw_node_free_ref(next_gw);
+        if (router)
+                neigh_node_free_ref(router);
 }
 
 void gw_check_election(struct bat_priv *bat_priv, struct orig_node *orig_node)
@@ -360,7 +396,7 @@ void gw_node_purge(struct bat_priv *bat_priv)
         struct gw_node *gw_node, *curr_gw;
         struct hlist_node *node, *node_tmp;
         unsigned long timeout = 2 * PURGE_TIMEOUT * HZ;
-        char do_deselect = 0;
+        int do_deselect = 0;
 
         curr_gw = gw_get_selected_gw_node(bat_priv);
 
@@ -479,14 +515,75 @@ out:
         return ret;
 }
 
-int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb)
+static bool is_type_dhcprequest(struct sk_buff *skb, int header_len)
+{
+        int ret = false;
+        unsigned char *p;
+        int pkt_len;
+
+        if (skb_linearize(skb) < 0)
+                goto out;
+
+        pkt_len = skb_headlen(skb);
+
+        if (pkt_len < header_len + DHCP_OPTIONS_OFFSET + 1)
+                goto out;
+
+        p = skb->data + header_len + DHCP_OPTIONS_OFFSET;
+        pkt_len -= header_len + DHCP_OPTIONS_OFFSET + 1;
+
+        /* Access the dhcp option lists. Each entry is made up by:
+         * - octect 1: option type
+         * - octect 2: option data len (only if type != 255 and 0)
+         * - octect 3: option data */
+        while (*p != 255 && !ret) {
+                /* p now points to the first octect: option type */
+                if (*p == 53) {
+                        /* type 53 is the message type option.
+                         * Jump the len octect and go to the data octect */
+                        if (pkt_len < 2)
+                                goto out;
+                        p += 2;
+
+                        /* check if the message type is what we need */
+                        if (*p == DHCP_REQUEST)
+                                ret = true;
+                        break;
+                } else if (*p == 0) {
+                        /* option type 0 (padding), just go forward */
+                        if (pkt_len < 1)
+                                goto out;
+                        pkt_len--;
+                        p++;
+                } else {
+                        /* This is any other option. So we get the length... */
+                        if (pkt_len < 1)
+                                goto out;
+                        pkt_len--;
+                        p++;
+
+                        /* ...and then we jump over the data */
+                        if (pkt_len < *p)
+                                goto out;
+                        pkt_len -= *p;
+                        p += (*p);
+                }
+        }
+out:
+        return ret;
+}
+
+int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb,
+                 struct orig_node *old_gw)
 {
         struct ethhdr *ethhdr;
         struct iphdr *iphdr;
         struct ipv6hdr *ipv6hdr;
         struct udphdr *udphdr;
         struct gw_node *curr_gw;
+        struct neigh_node *neigh_curr = NULL, *neigh_old = NULL;
         unsigned int header_len = 0;
+        int ret = 1;
 
         if (atomic_read(&bat_priv->gw_mode) == GW_MODE_OFF)
                 return 0;
@@ -554,7 +651,30 @@ int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb)
         if (!curr_gw)
                 return 0;
 
+        /* If old_gw != NULL then this packet is unicast.
+         * So, at this point we have to check the message type: if it is a
+         * DHCPREQUEST we have to decide whether to drop it or not */
+        if (old_gw && curr_gw->orig_node != old_gw) {
+                if (is_type_dhcprequest(skb, header_len)) {
+                        /* If the dhcp packet has been sent to a different gw,
+                         * we have to evaluate whether the old gw is still
+                         * reliable enough */
+                        neigh_curr = find_router(bat_priv, curr_gw->orig_node,
+                                                 NULL);
+                        neigh_old = find_router(bat_priv, old_gw, NULL);
+                        if (!neigh_curr || !neigh_old)
+                                goto free_neigh;
+                        if (neigh_curr->tq_avg - neigh_old->tq_avg <
+                                                                GW_THRESHOLD)
+                                ret = -1;
+                }
+        }
+free_neigh:
+        if (neigh_old)
+                neigh_node_free_ref(neigh_old);
+        if (neigh_curr)
+                neigh_node_free_ref(neigh_curr);
         if (curr_gw)
                 gw_node_free_ref(curr_gw);
-        return 1;
+        return ret;
 }