batman-adv: refactoring gateway handling code

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Acked-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

3 files changed, 126 insertions, 75 deletions

diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index 619fb73b3b76..9373a143c6d4 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -25,6 +25,7 @@
 #include "gateway_common.h"
 #include "hard-interface.h"
 #include "originator.h"
+#include "translation-table.h"
 #include "routing.h"
 #include <linux/ip.h>
 #include <linux/ipv6.h>
@@ -572,108 +573,142 @@ out:
         return ret;
 }
 
-int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb,
-                 struct orig_node *old_gw)
+bool gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len)
 {
         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;
 
         /* check for ethernet header */
-        if (!pskb_may_pull(skb, header_len + ETH_HLEN))
-                return 0;
+        if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
+                return false;
         ethhdr = (struct ethhdr *)skb->data;
-        header_len += ETH_HLEN;
+        *header_len += ETH_HLEN;
 
         /* check for initial vlan header */
         if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
-                if (!pskb_may_pull(skb, header_len + VLAN_HLEN))
-                        return 0;
+                if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
+                        return false;
                 ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);
-                header_len += VLAN_HLEN;
+                *header_len += VLAN_HLEN;
         }
 
         /* check for ip header */
         switch (ntohs(ethhdr->h_proto)) {
         case ETH_P_IP:
-                if (!pskb_may_pull(skb, header_len + sizeof(*iphdr)))
-                        return 0;
-                iphdr = (struct iphdr *)(skb->data + header_len);
-                header_len += iphdr->ihl * 4;
+                if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
+                        return false;
+                iphdr = (struct iphdr *)(skb->data + *header_len);
+                *header_len += iphdr->ihl * 4;
 
                 /* check for udp header */
                 if (iphdr->protocol != IPPROTO_UDP)
-                        return 0;
+                        return false;
 
                 break;
         case ETH_P_IPV6:
-                if (!pskb_may_pull(skb, header_len + sizeof(*ipv6hdr)))
-                        return 0;
-                ipv6hdr = (struct ipv6hdr *)(skb->data + header_len);
-                header_len += sizeof(*ipv6hdr);
+                if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
+                        return false;
+                ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
+                *header_len += sizeof(*ipv6hdr);
 
                 /* check for udp header */
                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
-                        return 0;
+                        return false;
 
                 break;
         default:
-                return 0;
+                return false;
         }
 
-        if (!pskb_may_pull(skb, header_len + sizeof(*udphdr)))
-                return 0;
-        udphdr = (struct udphdr *)(skb->data + header_len);
-        header_len += sizeof(*udphdr);
+        if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
+                return false;
+        udphdr = (struct udphdr *)(skb->data + *header_len);
+        *header_len += sizeof(*udphdr);
 
         /* check for bootp port */
         if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&
              (ntohs(udphdr->dest) != 67))
-                return 0;
+                return false;
 
         if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&
             (ntohs(udphdr->dest) != 547))
-                return 0;
+                return false;
 
-        if (atomic_read(&bat_priv->gw_mode) == GW_MODE_SERVER)
-                return -1;
+        return true;
+}
 
-        curr_gw = gw_get_selected_gw_node(bat_priv);
-        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;
-                }
+bool gw_out_of_range(struct bat_priv *bat_priv,
+                     struct sk_buff *skb, struct ethhdr *ethhdr)
+{
+        struct neigh_node *neigh_curr = NULL, *neigh_old = NULL;
+        struct orig_node *orig_dst_node = NULL;
+        struct gw_node *curr_gw = NULL;
+        bool ret, out_of_range = false;
+        unsigned int header_len = 0;
+        uint8_t curr_tq_avg;
+
+        ret = gw_is_dhcp_target(skb, &header_len);
+        if (!ret)
+                goto out;
+
+        orig_dst_node = transtable_search(bat_priv, ethhdr->h_source,
+                                          ethhdr->h_dest);
+        if (!orig_dst_node)
+                goto out;
+
+        if (!orig_dst_node->gw_flags)
+                goto out;
+
+        ret = is_type_dhcprequest(skb, header_len);
+        if (!ret)
+                goto out;
+
+        switch (atomic_read(&bat_priv->gw_mode)) {
+        case GW_MODE_SERVER:
+                /* If we are a GW then we are our best GW. We can artificially
+                 * set the tq towards ourself as the maximum value */
+                curr_tq_avg = TQ_MAX_VALUE;
+                break;
+        case GW_MODE_CLIENT:
+                curr_gw = gw_get_selected_gw_node(bat_priv);
+                if (!curr_gw)
+                        goto out;
+
+                /* packet is going to our gateway */
+                if (curr_gw->orig_node == orig_dst_node)
+                        goto out;
+
+                /* 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);
+                if (!neigh_curr)
+                        goto out;
+
+                curr_tq_avg = neigh_curr->tq_avg;
+                break;
+        case GW_MODE_OFF:
+        default:
+                goto out;
         }
-free_neigh:
+
+        neigh_old = find_router(bat_priv, orig_dst_node, NULL);
+        if (!!neigh_old)
+                goto out;
+
+        if (curr_tq_avg - neigh_old->tq_avg > GW_THRESHOLD)
+                out_of_range = true;
+
+out:
+        if (orig_dst_node)
+                orig_node_free_ref(orig_dst_node);
+        if (curr_gw)
+                gw_node_free_ref(curr_gw);
         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 ret;
+        return out_of_range;
 }
diff --git a/net/batman-adv/gateway_client.h b/net/batman-adv/gateway_client.h
index b9b983c07feb..e1edba08eb1d 100644
--- a/net/batman-adv/gateway_client.h
+++ b/net/batman-adv/gateway_client.h
@@ -31,7 +31,8 @@ void gw_node_update(struct bat_priv *bat_priv,
 void gw_node_delete(struct bat_priv *bat_priv, struct orig_node *orig_node);
 void gw_node_purge(struct bat_priv *bat_priv);
 int gw_client_seq_print_text(struct seq_file *seq, void *offset);
-int gw_is_target(struct bat_priv *bat_priv, struct sk_buff *skb,
-                 struct orig_node *old_gw);
+bool gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len);
+bool gw_out_of_range(struct bat_priv *bat_priv,
+                     struct sk_buff *skb, struct ethhdr *ethhdr);
 
 #endif /* _NET_BATMAN_ADV_GATEWAY_CLIENT_H_ */
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index f9cc95728989..45297c843092 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -563,10 +563,10 @@ static int interface_tx(struct sk_buff *skb, struct net_device *soft_iface)
         struct bcast_packet *bcast_packet;
         struct vlan_ethhdr *vhdr;
         struct softif_neigh *curr_softif_neigh = NULL;
-        struct orig_node *orig_node = NULL;
+        unsigned int header_len = 0;
         int data_len = skb->len, ret;
         short vid = -1;
-        bool do_bcast;
+        bool do_bcast = false;
 
         if (atomic_read(&bat_priv->mesh_state) != MESH_ACTIVE)
                 goto dropped;
@@ -598,17 +598,28 @@ static int interface_tx(struct sk_buff *skb, struct net_device *soft_iface)
         /* Register the client MAC in the transtable */
         tt_local_add(soft_iface, ethhdr->h_source, skb->skb_iif);
 
-        orig_node = transtable_search(bat_priv, ethhdr->h_source,
-                                      ethhdr->h_dest);
-        do_bcast = is_multicast_ether_addr(ethhdr->h_dest);
-        if (do_bcast || (orig_node && orig_node->gw_flags)) {
-                ret = gw_is_target(bat_priv, skb, orig_node);
+        if (is_multicast_ether_addr(ethhdr->h_dest)) {
+                do_bcast = true;
 
-                if (ret < 0)
-                        goto dropped;
-
-                if (ret)
-                        do_bcast = false;
+                switch (atomic_read(&bat_priv->gw_mode)) {
+                case GW_MODE_SERVER:
+                        /* gateway servers should not send dhcp
+                         * requests into the mesh */
+                        ret = gw_is_dhcp_target(skb, &header_len);
+                        if (ret)
+                                goto dropped;
+                        break;
+                case GW_MODE_CLIENT:
+                        /* gateway clients should send dhcp requests
+                         * via unicast to their gateway */
+                        ret = gw_is_dhcp_target(skb, &header_len);
+                        if (ret)
+                                do_bcast = false;
+                        break;
+                case GW_MODE_OFF:
+                default:
+                        break;
+                }
         }
 
         /* ethernet packet should be broadcasted */
@@ -644,6 +655,12 @@ static int interface_tx(struct sk_buff *skb, struct net_device *soft_iface)
 
         /* unicast packet */
         } else {
+                if (atomic_read(&bat_priv->gw_mode) != GW_MODE_OFF) {
+                        ret = gw_out_of_range(bat_priv, skb, ethhdr);
+                        if (ret)
+                                goto dropped;
+                }
+
                 ret = unicast_send_skb(skb, bat_priv);
                 if (ret != 0)
                         goto dropped_freed;
@@ -662,8 +679,6 @@ end:
                 softif_neigh_free_ref(curr_softif_neigh);
         if (primary_if)
                 hardif_free_ref(primary_if);
-        if (orig_node)
-                orig_node_free_ref(orig_node);
         return NETDEV_TX_OK;
 }