path: root/net/batman-adv/send.c

/* Copyright (C) 2007-2016  B.A.T.M.A.N. contributors:
 *
 * Marek Lindner, Simon Wunderlich
 *
 * 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 "send.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/byteorder/generic.h>
#include <linux/errno.h>
#include <linux/etherdevice.h>
#include <linux/fs.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/printk.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/workqueue.h>

#include "distributed-arp-table.h"
#include "fragmentation.h"
#include "gateway_client.h"
#include "hard-interface.h"
#include "log.h"
#include "network-coding.h"
#include "originator.h"
#include "routing.h"
#include "soft-interface.h"
#include "translation-table.h"

static void batadv_send_outstanding_bcast_packet(struct work_struct *work);

/**
 * batadv_send_skb_packet - send an already prepared packet
 * @skb: the packet to send
 * @hard_iface: the interface to use to send the broadcast packet
 * @dst_addr: the payload destination
 *
 * Send out an already prepared packet to the given neighbor or broadcast it
 * using the specified interface. Either hard_iface or neigh_node must be not
 * NULL.
 * If neigh_node is NULL, then the packet is broadcasted using hard_iface,
 * otherwise it is sent as unicast to the given neighbor.
 *
 * Return: NET_TX_DROP in case of error or the result of dev_queue_xmit(skb)
 * otherwise
 */
int batadv_send_skb_packet(struct sk_buff *skb,
			   struct batadv_hard_iface *hard_iface,
			   const u8 *dst_addr)
{
	struct batadv_priv *bat_priv;
	struct ethhdr *ethhdr;
	int ret;

	bat_priv = netdev_priv(hard_iface->soft_iface);

	if (hard_iface->if_status != BATADV_IF_ACTIVE)
		goto send_skb_err;

	if (unlikely(!hard_iface->net_dev))
		goto send_skb_err;

	if (!(hard_iface->net_dev->flags & IFF_UP)) {
		pr_warn("Interface %s is not up - can't send packet via that interface!\n",
			hard_iface->net_dev->name);
		goto send_skb_err;
	}

	/* push to the ethernet header. */
	if (batadv_skb_head_push(skb, ETH_HLEN) < 0)
		goto send_skb_err;

	skb_reset_mac_header(skb);

	ethhdr = eth_hdr(skb);
	ether_addr_copy(ethhdr->h_source, hard_iface->net_dev->dev_addr);
	ether_addr_copy(ethhdr->h_dest, dst_addr);
	ethhdr->h_proto = htons(ETH_P_BATMAN);

	skb_set_network_header(skb, ETH_HLEN);
	skb->protocol = htons(ETH_P_BATMAN);

	skb->dev = hard_iface->net_dev;

	/* Save a clone of the skb to use when decoding coded packets */
	batadv_nc_skb_store_for_decoding(bat_priv, skb);

	/* dev_queue_xmit() returns a negative result on error.	 However on
	 * congestion and traffic shaping, it drops and returns NET_XMIT_DROP
	 * (which is > 0). This will not be treated as an error.
	 *
	 * a negative value cannot be returned because it could be interepreted
	 * as not consumed skb by callers of batadv_send_skb_to_orig.
	 */
	ret = dev_queue_xmit(skb);
	if (ret < 0)
		ret = NET_XMIT_DROP;

	return ret;
send_skb_err:
	kfree_skb(skb);
	return NET_XMIT_DROP;
}

int batadv_send_broadcast_skb(struct sk_buff *skb,
			      struct batadv_hard_iface *hard_iface)
{
	return batadv_send_skb_packet(skb, hard_iface, batadv_broadcast_addr);
}

int batadv_send_unicast_skb(struct sk_buff *skb,
			    struct batadv_neigh_node *neigh)
{
#ifdef CONFIG_BATMAN_ADV_BATMAN_V
	struct batadv_hardif_neigh_node *hardif_neigh;
#endif
	int ret;

	ret = batadv_send_skb_packet(skb, neigh->if_incoming, neigh->addr);

#ifdef CONFIG_BATMAN_ADV_BATMAN_V
	hardif_neigh = batadv_hardif_neigh_get(neigh->if_incoming, neigh->addr);

	if ((hardif_neigh) && (ret != NET_XMIT_DROP))
		hardif_neigh->bat_v.last_unicast_tx = jiffies;

	if (hardif_neigh)
		batadv_hardif_neigh_put(hardif_neigh);
#endif

	return ret;
}

/**
 * batadv_send_skb_to_orig - Lookup next-hop and transmit skb.
 * @skb: Packet to be transmitted.
 * @orig_node: Final destination of the packet.
 * @recv_if: Interface used when receiving the packet (can be NULL).
 *
 * Looks up the best next-hop towards the passed originator and passes the
 * skb on for preparation of MAC header. If the packet originated from this
 * host, NULL can be passed as recv_if and no interface alternating is
 * attempted.
 *
 * Return: -1 on failure (and the skb is not consumed), -EINPROGRESS if the
 * skb is buffered for later transmit or the NET_XMIT status returned by the
 * lower routine if the packet has been passed down.
 *
 * If the returning value is not -1 the skb has been consumed.
 */
int batadv_send_skb_to_orig(struct sk_buff *skb,
			    struct batadv_orig_node *orig_node,
			    struct batadv_hard_iface *recv_if)
{
	struct batadv_priv *bat_priv = orig_node->bat_priv;
	struct batadv_neigh_node *neigh_node;
	int ret = -1;

	/* batadv_find_router() increases neigh_nodes refcount if found. */
	neigh_node = batadv_find_router(bat_priv, orig_node, recv_if);
	if (!neigh_node)
		goto out;

	/* Check if the skb is too large to send in one piece and fragment
	 * it if needed.
	 */
	if (atomic_read(&bat_priv->fragmentation) &&
	    skb->len > neigh_node->if_incoming->net_dev->mtu) {
		/* Fragment and send packet. */
		ret = batadv_frag_send_packet(skb, orig_node, neigh_node);

		goto out;
	}

	/* try to network code the packet, if it is received on an interface
	 * (i.e. being forwarded). If the packet originates from this node or if
	 * network coding fails, then send the packet as usual.
	 */
	if (recv_if && batadv_nc_skb_forward(skb, neigh_node))
		ret = -EINPROGRESS;
	else
		ret = batadv_send_unicast_skb(skb, neigh_node);

out:
	if (neigh_node)
		batadv_neigh_node_put(neigh_node);

	return ret;
}

/**
 * batadv_send_skb_push_fill_unicast - extend the buffer and initialize the
 *  common fields for unicast packets
 * @skb: the skb carrying the unicast header to initialize
 * @hdr_size: amount of bytes to push at the beginning of the skb
 * @orig_node: the destination node
 *
 * Return: false if the buffer extension was not possible or true otherwise.
 */
static bool
batadv_send_skb_push_fill_unicast(struct sk_buff *skb, int hdr_size,
				  struct batadv_orig_node *orig_node)
{
	struct batadv_unicast_packet *unicast_packet;
	u8 ttvn = (u8)atomic_read(&orig_node->last_ttvn);

	if (batadv_skb_head_push(skb, hdr_size) < 0)
		return false;

	unicast_packet = (struct batadv_unicast_packet *)skb->data;
	unicast_packet->version = BATADV_COMPAT_VERSION;
	/* batman packet type: unicast */
	unicast_packet->packet_type = BATADV_UNICAST;
	/* set unicast ttl */
	unicast_packet->ttl = BATADV_TTL;
	/* copy the destination for faster routing */
	ether_addr_copy(unicast_packet->dest, orig_node->orig);
	/* set the destination tt version number */
	unicast_packet->ttvn = ttvn;

	return true;
}

/**
 * batadv_send_skb_prepare_unicast - encapsulate an skb with a unicast header
 * @skb: the skb containing the payload to encapsulate
 * @orig_node: the destination node
 *
 * Return: false if the payload could not be encapsulated or true otherwise.
 */
static bool batadv_send_skb_prepare_unicast(struct sk_buff *skb,
					    struct batadv_orig_node *orig_node)
{
	size_t uni_size = sizeof(struct batadv_unicast_packet);

	return batadv_send_skb_push_fill_unicast(skb, uni_size, orig_node);
}