diff options
Diffstat (limited to 'net/batman-adv/gateway_client.c')
| -rw-r--r-- | net/batman-adv/gateway_client.c | 881 |
1 files changed, 881 insertions, 0 deletions
diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c new file mode 100644 index 000000000..090828cf1 --- /dev/null +++ b/net/batman-adv/gateway_client.c @@ -0,0 +1,881 @@ +/* Copyright (C) 2009-2014 B.A.T.M.A.N. contributors: + * + * Marek Lindner + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#include "main.h" +#include "sysfs.h" +#include "gateway_client.h" +#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> +#include <linux/udp.h> +#include <linux/if_vlan.h> + +/* These are the offsets of the "hw type" and "hw address length" in the dhcp + * packet starting at the beginning of the dhcp header + */ +#define BATADV_DHCP_HTYPE_OFFSET 1 +#define BATADV_DHCP_HLEN_OFFSET 2 +/* Value of htype representing Ethernet */ +#define BATADV_DHCP_HTYPE_ETHERNET 0x01 +/* This is the offset of the "chaddr" field in the dhcp packet starting at the + * beginning of the dhcp header + */ +#define BATADV_DHCP_CHADDR_OFFSET 28 + +static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node) +{ + if (atomic_dec_and_test(&gw_node->refcount)) { + batadv_orig_node_free_ref(gw_node->orig_node); + kfree_rcu(gw_node, rcu); + } +} + +static struct batadv_gw_node * +batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv) +{ + struct batadv_gw_node *gw_node; + + rcu_read_lock(); + gw_node = rcu_dereference(bat_priv->gw.curr_gw); + if (!gw_node) + goto out; + + if (!atomic_inc_not_zero(&gw_node->refcount)) + gw_node = NULL; + +out: + rcu_read_unlock(); + return gw_node; +} + +struct batadv_orig_node * +batadv_gw_get_selected_orig(struct batadv_priv *bat_priv) +{ + struct batadv_gw_node *gw_node; + struct batadv_orig_node *orig_node = NULL; + + gw_node = batadv_gw_get_selected_gw_node(bat_priv); + if (!gw_node) + goto out; + + rcu_read_lock(); + orig_node = gw_node->orig_node; + if (!orig_node) + goto unlock; + + if (!atomic_inc_not_zero(&orig_node->refcount)) + orig_node = NULL; + +unlock: + rcu_read_unlock(); +out: + if (gw_node) + batadv_gw_node_free_ref(gw_node); + return orig_node; +} + +static void batadv_gw_select(struct batadv_priv *bat_priv, + struct batadv_gw_node *new_gw_node) +{ + struct batadv_gw_node *curr_gw_node; + + spin_lock_bh(&bat_priv->gw.list_lock); + + if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount)) + new_gw_node = NULL; + + curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1); + rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node); + + if (curr_gw_node) + batadv_gw_node_free_ref(curr_gw_node); + + spin_unlock_bh(&bat_priv->gw.list_lock); +} + +/** + * batadv_gw_reselect - force a gateway reselection + * @bat_priv: the bat priv with all the soft interface information + * + * Set a flag to remind the GW component to perform a new gateway reselection. + * However this function does not ensure that the current gateway is going to be + * deselected. The reselection mechanism may elect the same gateway once again. + * + * This means that invoking batadv_gw_reselect() does not guarantee a gateway + * change and therefore a uevent is not necessarily expected. + */ +void batadv_gw_reselect(struct batadv_priv *bat_priv) +{ + atomic_set(&bat_priv->gw.reselect, 1); +} + +static struct batadv_gw_node * +batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv) +{ + struct batadv_neigh_node *router; + struct batadv_neigh_ifinfo *router_ifinfo; + struct batadv_gw_node *gw_node, *curr_gw = NULL; + uint32_t max_gw_factor = 0, tmp_gw_factor = 0; + uint32_t gw_divisor; + uint8_t max_tq = 0; + uint8_t tq_avg; + struct batadv_orig_node *orig_node; + + gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE; + gw_divisor *= 64; + + rcu_read_lock(); + hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) { + if (gw_node->deleted) + continue; + + orig_node = gw_node->orig_node; + router = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT); + if (!router) + continue; + + router_ifinfo = batadv_neigh_ifinfo_get(router, + BATADV_IF_DEFAULT); + if (!router_ifinfo) + goto next; + + if (!atomic_inc_not_zero(&gw_node->refcount)) + goto next; + + tq_avg = router_ifinfo->bat_iv.tq_avg; + + switch (atomic_read(&bat_priv->gw_sel_class)) { + case 1: /* fast connection */ + tmp_gw_factor = tq_avg * tq_avg; + tmp_gw_factor *= gw_node->bandwidth_down; + tmp_gw_factor *= 100 * 100; + tmp_gw_factor /= gw_divisor; + + if ((tmp_gw_factor > max_gw_factor) || + ((tmp_gw_factor == max_gw_factor) && + (tq_avg > max_tq))) { + if (curr_gw) + batadv_gw_node_free_ref(curr_gw); + curr_gw = gw_node; + atomic_inc(&curr_gw->refcount); + } + break; + + default: /* 2: stable connection (use best statistic) + * 3: fast-switch (use best statistic but change as + * soon as a better gateway appears) + * XX: late-switch (use best statistic but change as + * soon as a better gateway appears which has + * $routing_class more tq points) + */ + if (tq_avg > max_tq) { + if (curr_gw) + batadv_gw_node_free_ref(curr_gw); + curr_gw = gw_node; + atomic_inc(&curr_gw->refcount); + } + break; + } + + if (tq_avg > max_tq) + max_tq = tq_avg; + + if (tmp_gw_factor > max_gw_factor) + max_gw_factor = tmp_gw_factor; + + batadv_gw_node_free_ref(gw_node); + +next: + batadv_neigh_node_free_ref(router); + if (router_ifinfo) + batadv_neigh_ifinfo_free_ref(router_ifinfo); + } + rcu_read_unlock(); + + return curr_gw; +} + +/** + * batadv_gw_check_client_stop - check if client mode has been switched off + * @bat_priv: the bat priv with all the soft interface information + * + * This function assumes the caller has checked that the gw state *is actually + * changing*. This function is not supposed to be called when there is no state + * change. + */ +void batadv_gw_check_client_stop(struct batadv_priv *bat_priv) +{ + struct batadv_gw_node *curr_gw; + + if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT) + return; + + curr_gw = batadv_gw_get_selected_gw_node(bat_priv); + if (!curr_gw) + return; + + /* deselect the current gateway so that next time that client mode is + * enabled a proper GW_ADD event can be sent + */ + batadv_gw_select(bat_priv, NULL); + + /* if batman-adv is switching the gw client mode off and a gateway was + * already selected, send a DEL uevent + */ + batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL); + + batadv_gw_node_free_ref(curr_gw); +} + +void batadv_gw_election(struct batadv_priv *bat_priv) +{ + struct batadv_gw_node *curr_gw = NULL, *next_gw = NULL; + struct batadv_neigh_node *router = NULL; + struct batadv_neigh_ifinfo *router_ifinfo = NULL; + char gw_addr[18] = { '\0' }; + + if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT) + goto out; + + curr_gw = batadv_gw_get_selected_gw_node(bat_priv); + + if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw) + goto out; + + next_gw = batadv_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 = batadv_orig_router_get(next_gw->orig_node, + BATADV_IF_DEFAULT); + if (!router) { + batadv_gw_reselect(bat_priv); + goto out; + } + + router_ifinfo = batadv_neigh_ifinfo_get(router, + BATADV_IF_DEFAULT); + if (!router_ifinfo) { + batadv_gw_reselect(bat_priv); + goto out; + } + } + + if ((curr_gw) && (!next_gw)) { + batadv_dbg(BATADV_DBG_BATMAN, bat_priv, + "Removing selected gateway - no gateway in range\n"); + batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, + NULL); + } else if ((!curr_gw) && (next_gw)) { + batadv_dbg(BATADV_DBG_BATMAN, bat_priv, + "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", + next_gw->orig_node->orig, + next_gw->bandwidth_down / 10, + next_gw->bandwidth_down % 10, + next_gw->bandwidth_up / 10, + next_gw->bandwidth_up % 10, + router_ifinfo->bat_iv.tq_avg); + batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD, + gw_addr); + } else { + batadv_dbg(BATADV_DBG_BATMAN, bat_priv, + "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", + next_gw->orig_node->orig, + next_gw->bandwidth_down / 10, + next_gw->bandwidth_down % 10, + next_gw->bandwidth_up / 10, + next_gw->bandwidth_up % 10, + router_ifinfo->bat_iv.tq_avg); + batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE, + gw_addr); + } + + batadv_gw_select(bat_priv, next_gw); + +out: + if (curr_gw) + batadv_gw_node_free_ref(curr_gw); + if (next_gw) + batadv_gw_node_free_ref(next_gw); + if (router) + batadv_neigh_node_free_ref(router); + if (router_ifinfo) + batadv_neigh_ifinfo_free_ref(router_ifinfo); +} + +void batadv_gw_check_election(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig_node) +{ + struct batadv_neigh_ifinfo *router_orig_tq = NULL; + struct batadv_neigh_ifinfo *router_gw_tq = NULL; + struct batadv_orig_node *curr_gw_orig; + struct batadv_neigh_node *router_gw = NULL, *router_orig = NULL; + uint8_t gw_tq_avg, orig_tq_avg; + + curr_gw_orig = batadv_gw_get_selected_orig(bat_priv); + if (!curr_gw_orig) + goto reselect; + + router_gw = batadv_orig_router_get(curr_gw_orig, BATADV_IF_DEFAULT); + if (!router_gw) + goto reselect; + + router_gw_tq = batadv_neigh_ifinfo_get(router_gw, + BATADV_IF_DEFAULT); + if (!router_gw_tq) + goto reselect; + + /* this node already is the gateway */ + if (curr_gw_orig == orig_node) + goto out; + + router_orig = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT); + if (!router_orig) + goto out; + + router_orig_tq = batadv_neigh_ifinfo_get(router_orig, + BATADV_IF_DEFAULT); + if (!router_orig_tq) + goto out; + + gw_tq_avg = router_gw_tq->bat_iv.tq_avg; + orig_tq_avg = router_orig_tq->bat_iv.tq_avg; + + /* the TQ value has to be better */ + if (orig_tq_avg < gw_tq_avg) + goto out; + + /* if the routing class is greater than 3 the value tells us how much + * greater the TQ value of the new gateway must be + */ + if ((atomic_read(&bat_priv->gw_sel_class) > 3) && + (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class))) + goto out; + + batadv_dbg(BATADV_DBG_BATMAN, bat_priv, + "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n", + gw_tq_avg, orig_tq_avg); + +reselect: + batadv_gw_reselect(bat_priv); +out: + if (curr_gw_orig) + batadv_orig_node_free_ref(curr_gw_orig); + if (router_gw) + batadv_neigh_node_free_ref(router_gw); + if (router_orig) + batadv_neigh_node_free_ref(router_orig); + if (router_gw_tq) + batadv_neigh_ifinfo_free_ref(router_gw_tq); + if (router_orig_tq) + batadv_neigh_ifinfo_free_ref(router_orig_tq); +} + +/** + * batadv_gw_node_add - add gateway node to list of available gateways + * @bat_priv: the bat priv with all the soft interface information + * @orig_node: originator announcing gateway capabilities + * @gateway: announced bandwidth information + */ +static void batadv_gw_node_add(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig_node, + struct batadv_tvlv_gateway_data *gateway) +{ + struct batadv_gw_node *gw_node; + + if (gateway->bandwidth_down == 0) + return; + + if (!atomic_inc_not_zero(&orig_node->refcount)) + return; + + gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC); + if (!gw_node) { + batadv_orig_node_free_ref(orig_node); + return; + } + + INIT_HLIST_NODE(&gw_node->list); + gw_node->orig_node = orig_node; + atomic_set(&gw_node->refcount, 1); + + spin_lock_bh(&bat_priv->gw.list_lock); + hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list); + spin_unlock_bh(&bat_priv->gw.list_lock); + + batadv_dbg(BATADV_DBG_BATMAN, bat_priv, + "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n", + orig_node->orig, + ntohl(gateway->bandwidth_down) / 10, + ntohl(gateway->bandwidth_down) % 10, + ntohl(gateway->bandwidth_up) / 10, + ntohl(gateway->bandwidth_up) % 10); +} + +/** + * batadv_gw_node_get - retrieve gateway node from list of available gateways + * @bat_priv: the bat priv with all the soft interface information + * @orig_node: originator announcing gateway capabilities + * + * Returns gateway node if found or NULL otherwise. + */ +static struct batadv_gw_node * +batadv_gw_node_get(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig_node) +{ + struct batadv_gw_node *gw_node_tmp, *gw_node = NULL; + + rcu_read_lock(); + hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.list, list) { + if (gw_node_tmp->orig_node != orig_node) + continue; + + if (gw_node_tmp->deleted) + continue; + + if (!atomic_inc_not_zero(&gw_node_tmp->refcount)) + continue; + + gw_node = gw_node_tmp; + break; + } + rcu_read_unlock(); + + return gw_node; +} + +/** + * batadv_gw_node_update - update list of available gateways with changed + * bandwidth information + * @bat_priv: the bat priv with all the soft interface information + * @orig_node: originator announcing gateway capabilities + * @gateway: announced bandwidth information + */ +void batadv_gw_node_update(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig_node, + struct batadv_tvlv_gateway_data *gateway) +{ + struct batadv_gw_node *gw_node, *curr_gw = NULL; + + gw_node = batadv_gw_node_get(bat_priv, orig_node); + if (!gw_node) { + batadv_gw_node_add(bat_priv, orig_node, gateway); + goto out; + } + + if ((gw_node->bandwidth_down == ntohl(gateway->bandwidth_down)) && + (gw_node->bandwidth_up == ntohl(gateway->bandwidth_up))) + goto out; + + batadv_dbg(BATADV_DBG_BATMAN, bat_priv, + "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n", + orig_node->orig, + gw_node->bandwidth_down / 10, + gw_node->bandwidth_down % 10, + gw_node->bandwidth_up / 10, + gw_node->bandwidth_up % 10, + ntohl(gateway->bandwidth_down) / 10, + ntohl(gateway->bandwidth_down) % 10, + ntohl(gateway->bandwidth_up) / 10, + ntohl(gateway->bandwidth_up) % 10); + + gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); + gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); + + gw_node->deleted = 0; + if (ntohl(gateway->bandwidth_down) == 0) { + gw_node->deleted = jiffies; + batadv_dbg(BATADV_DBG_BATMAN, bat_priv, + "Gateway %pM removed from gateway list\n", + orig_node->orig); + + /* Note: We don't need a NULL check here, since curr_gw never + * gets dereferenced. + */ + curr_gw = batadv_gw_get_selected_gw_node(bat_priv); + if (gw_node == curr_gw) + batadv_gw_reselect(bat_priv); + } + +out: + if (curr_gw) + batadv_gw_node_free_ref(curr_gw); + if (gw_node) + batadv_gw_node_free_ref(gw_node); +} + +void batadv_gw_node_delete(struct batadv_priv *bat_priv, + struct batadv_orig_node *orig_node) +{ + struct batadv_tvlv_gateway_data gateway; + + gateway.bandwidth_down = 0; + gateway.bandwidth_up = 0; + + batadv_gw_node_update(bat_priv, orig_node, &gateway); +} + +void batadv_gw_node_purge(struct batadv_priv *bat_priv) +{ + struct batadv_gw_node *gw_node, *curr_gw; + struct hlist_node *node_tmp; + unsigned long timeout = msecs_to_jiffies(2 * BATADV_PURGE_TIMEOUT); + int do_reselect = 0; + + curr_gw = batadv_gw_get_selected_gw_node(bat_priv); + + spin_lock_bh(&bat_priv->gw.list_lock); + + hlist_for_each_entry_safe(gw_node, node_tmp, + &bat_priv->gw.list, list) { + if (((!gw_node->deleted) || + (time_before(jiffies, gw_node->deleted + timeout))) && + atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE) + continue; + + if (curr_gw == gw_node) + do_reselect = 1; + + hlist_del_rcu(&gw_node->list); + batadv_gw_node_free_ref(gw_node); + } + + spin_unlock_bh(&bat_priv->gw.list_lock); + + /* gw_reselect() needs to acquire the gw_list_lock */ + if (do_reselect) + batadv_gw_reselect(bat_priv); + + if (curr_gw) + batadv_gw_node_free_ref(curr_gw); +} + +/* fails if orig_node has no router */ +static int batadv_write_buffer_text(struct batadv_priv *bat_priv, + struct seq_file *seq, + const struct batadv_gw_node *gw_node) +{ + struct batadv_gw_node *curr_gw; + struct batadv_neigh_node *router; + struct batadv_neigh_ifinfo *router_ifinfo = NULL; + int ret = -1; + + router = batadv_orig_router_get(gw_node->orig_node, BATADV_IF_DEFAULT); + if (!router) + goto out; + + router_ifinfo = batadv_neigh_ifinfo_get(router, BATADV_IF_DEFAULT); + if (!router_ifinfo) + goto out; + + curr_gw = batadv_gw_get_selected_gw_node(bat_priv); + + seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n", + (curr_gw == gw_node ? "=>" : " "), + gw_node->orig_node->orig, + router_ifinfo->bat_iv.tq_avg, router->addr, + router->if_incoming->net_dev->name, + gw_node->bandwidth_down / 10, + gw_node->bandwidth_down % 10, + gw_node->bandwidth_up / 10, + gw_node->bandwidth_up % 10); + ret = seq_has_overflowed(seq) ? -1 : 0; + + if (curr_gw) + batadv_gw_node_free_ref(curr_gw); +out: + if (router_ifinfo) + batadv_neigh_ifinfo_free_ref(router_ifinfo); + if (router) + batadv_neigh_node_free_ref(router); + return ret; +} + +int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset) +{ + struct net_device *net_dev = (struct net_device *)seq->private; + struct batadv_priv *bat_priv = netdev_priv(net_dev); + struct batadv_hard_iface *primary_if; + struct batadv_gw_node *gw_node; + int gw_count = 0; + + primary_if = batadv_seq_print_text_primary_if_get(seq); + if (!primary_if) + goto out; + + seq_printf(seq, + " %-12s (%s/%i) %17s [%10s]: advertised uplink bandwidth ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n", + "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF", + BATADV_SOURCE_VERSION, primary_if->net_dev->name, + primary_if->net_dev->dev_addr, net_dev->name); + + rcu_read_lock(); + hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) { + if (gw_node->deleted) + continue; + + /* fails if orig_node has no router */ + if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0) + continue; + + gw_count++; + } + rcu_read_unlock(); + + if (gw_count == 0) + seq_puts(seq, "No gateways in range ...\n"); + +out: + if (primary_if) + batadv_hardif_free_ref(primary_if); + return 0; +} + +/** + * batadv_gw_dhcp_recipient_get - check if a packet is a DHCP message + * @skb: the packet to check + * @header_len: a pointer to the batman-adv header size + * @chaddr: buffer where the client address will be stored. Valid + * only if the function returns BATADV_DHCP_TO_CLIENT + * + * Returns: + * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error + * while parsing it + * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server + * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client + * + * This function may re-allocate the data buffer of the skb passed as argument. + */ +enum batadv_dhcp_recipient +batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len, + uint8_t *chaddr) +{ + enum batadv_dhcp_recipient ret = BATADV_DHCP_NO; + struct ethhdr *ethhdr; + struct iphdr *iphdr; + struct ipv6hdr *ipv6hdr; + struct udphdr *udphdr; + struct vlan_ethhdr *vhdr; + int chaddr_offset; + __be16 proto; + uint8_t *p; + + /* check for ethernet header */ + if (!pskb_may_pull(skb, *header_len + ETH_HLEN)) + return BATADV_DHCP_NO; + + ethhdr = eth_hdr(skb); + proto = ethhdr->h_proto; + *header_len += ETH_HLEN; + + /* check for initial vlan header */ + if (proto == htons(ETH_P_8021Q)) { + if (!pskb_may_pull(skb, *header_len + VLAN_HLEN)) + return BATADV_DHCP_NO; + + vhdr = vlan_eth_hdr(skb); + proto = vhdr->h_vlan_encapsulated_proto; + *header_len += VLAN_HLEN; + } + + /* check for ip header */ + switch (proto) { + case htons(ETH_P_IP): + if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr))) + return BATADV_DHCP_NO; + + iphdr = (struct iphdr *)(skb->data + *header_len); + *header_len += iphdr->ihl * 4; + + /* check for udp header */ + if (iphdr->protocol != IPPROTO_UDP) + return BATADV_DHCP_NO; + + break; + case htons(ETH_P_IPV6): + if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr))) + return BATADV_DHCP_NO; + + ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len); + *header_len += sizeof(*ipv6hdr); + + /* check for udp header */ + if (ipv6hdr->nexthdr != IPPROTO_UDP) + return BATADV_DHCP_NO; + + break; + default: + return BATADV_DHCP_NO; + } + + if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr))) + return BATADV_DHCP_NO; + + /* skb->data might have been reallocated by pskb_may_pull() */ + ethhdr = eth_hdr(skb); + if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) + ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN); + + udphdr = (struct udphdr *)(skb->data + *header_len); + *header_len += sizeof(*udphdr); + + /* check for bootp port */ + switch (proto) { + case htons(ETH_P_IP): + if (udphdr->dest == htons(67)) + ret = BATADV_DHCP_TO_SERVER; + else if (udphdr->source == htons(67)) + ret = BATADV_DHCP_TO_CLIENT; + break; + case htons(ETH_P_IPV6): + if (udphdr->dest == htons(547)) + ret = BATADV_DHCP_TO_SERVER; + else if (udphdr->source == htons(547)) + ret = BATADV_DHCP_TO_CLIENT; + break; + } + + chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET; + /* store the client address if the message is going to a client */ + if (ret == BATADV_DHCP_TO_CLIENT && + pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) { + /* check if the DHCP packet carries an Ethernet DHCP */ + p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET; + if (*p != BATADV_DHCP_HTYPE_ETHERNET) + return BATADV_DHCP_NO; + + /* check if the DHCP packet carries a valid Ethernet address */ + p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET; + if (*p != ETH_ALEN) + return BATADV_DHCP_NO; + + ether_addr_copy(chaddr, skb->data + chaddr_offset); + } + + return ret; +} + +/** + * batadv_gw_out_of_range - check if the dhcp request destination is the best gw + * @bat_priv: the bat priv with all the soft interface information + * @skb: the outgoing packet + * + * Check if the skb is a DHCP request and if it is sent to the current best GW + * server. Due to topology changes it may be the case that the GW server + * previously selected is not the best one anymore. + * + * Returns true if the packet destination is unicast and it is not the best gw, + * false otherwise. + * + * This call might reallocate skb data. + * Must be invoked only when the DHCP packet is going TO a DHCP SERVER. + */ +bool batadv_gw_out_of_range(struct batadv_priv *bat_priv, + struct sk_buff *skb) +{ + struct batadv_neigh_node *neigh_curr = NULL, *neigh_old = NULL; + struct batadv_orig_node *orig_dst_node = NULL; + struct batadv_gw_node *gw_node = NULL, *curr_gw = NULL; + struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo; + struct ethhdr *ethhdr = (struct ethhdr *)skb->data; + bool out_of_range = false; + uint8_t curr_tq_avg; + unsigned short vid; + + vid = batadv_get_vid(skb, 0); + + orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source, + ethhdr->h_dest, vid); + if (!orig_dst_node) + goto out; + + gw_node = batadv_gw_node_get(bat_priv, orig_dst_node); + if (!gw_node) + goto out; + + switch (atomic_read(&bat_priv->gw_mode)) { + case BATADV_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 = BATADV_TQ_MAX_VALUE; + break; + case BATADV_GW_MODE_CLIENT: + curr_gw = batadv_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 = batadv_find_router(bat_priv, curr_gw->orig_node, + NULL); + if (!neigh_curr) + goto out; + + curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr, + BATADV_IF_DEFAULT); + if (!curr_ifinfo) + goto out; + + curr_tq_avg = curr_ifinfo->bat_iv.tq_avg; + batadv_neigh_ifinfo_free_ref(curr_ifinfo); + + break; + case BATADV_GW_MODE_OFF: + default: + goto out; + } + + neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL); + if (!neigh_old) + goto out; + + old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT); + if (!old_ifinfo) + goto out; + + if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD) + out_of_range = true; + batadv_neigh_ifinfo_free_ref(old_ifinfo); + +out: + if (orig_dst_node) + batadv_orig_node_free_ref(orig_dst_node); + if (curr_gw) + batadv_gw_node_free_ref(curr_gw); + if (gw_node) + batadv_gw_node_free_ref(gw_node); + if (neigh_old) + batadv_neigh_node_free_ref(neigh_old); + if (neigh_curr) + batadv_neigh_node_free_ref(neigh_curr); + return out_of_range; +} |