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OpenCloudOS-Kernel/net/batman-adv/gateway_client.c

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/* Copyright (C) 2009-2015 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 "gateway_client.h"
#include "main.h"
#include <linux/atomic.h>
#include <linux/byteorder/generic.h>
#include <linux/etherdevice.h>
#include <linux/fs.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/seq_file.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/udp.h>
#include "gateway_common.h"
#include "hard-interface.h"
#include "originator.h"
#include "packet.h"
#include "routing.h"
#include "sysfs.h"
#include "translation-table.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;
u64 max_gw_factor = 0;
u64 tmp_gw_factor = 0;
u8 max_tq = 0;
u8 tq_avg;
struct batadv_orig_node *orig_node;
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 >>= 18;
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;
struct batadv_gw_node *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;
struct batadv_neigh_node *router_orig = NULL;
u8 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;
gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
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,
u8 *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;
u8 *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;
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;
struct batadv_neigh_node *neigh_old = NULL;
struct batadv_orig_node *orig_dst_node = NULL;
struct batadv_gw_node *gw_node = NULL;
struct batadv_gw_node *curr_gw = NULL;
struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
bool out_of_range = false;
u8 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;
}
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