batman-adv: OGMv2 - add basic infrastructure

This is the initial implementation of the new OGM protocol
(version 2). It has been designed to work on top of the
newly added ELP.

In the previous version the OGM protocol was used to both
measure link qualities and flood the network with the metric
information. In this version the protocol is in charge of
the latter task only, leaving the former to ELP.

This means being able to decouple the interval used by the
neighbor discovery from the OGM broadcasting, which revealed
to be costly in dense networks and needed to be relaxed so
leading to a less responsive routing protocol.

Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>

1 files changed, 279 insertions, 0 deletions

diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c
new file mode 100644
index 000000000000..23932f9b85ec
--- /dev/null
+++ b/net/batman-adv/bat_v_ogm.c
@@ -0,0 +1,279 @@
+/* Copyright (C) 2013-2016 B.A.T.M.A.N. contributors:
+ *
+ * Antonio Quartulli
+ *
+ * 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 "bat_v_ogm.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_ether.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/random.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/stddef.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#include "hard-interface.h"
+#include "packet.h"
+#include "routing.h"
+#include "send.h"
+#include "translation-table.h"
+
+/**
+ * batadv_v_ogm_start_timer - restart the OGM sending timer
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+static void batadv_v_ogm_start_timer(struct batadv_priv *bat_priv)
+{
+	unsigned long msecs;
+	/* this function may be invoked in different contexts (ogm rescheduling
+	 * or hard_iface activation), but the work timer should not be reset
+	 */
+	if (delayed_work_pending(&bat_priv->bat_v.ogm_wq))
+		return;
+
+	msecs = atomic_read(&bat_priv->orig_interval) - BATADV_JITTER;
+	msecs += prandom_u32() % (2 * BATADV_JITTER);
+	queue_delayed_work(batadv_event_workqueue, &bat_priv->bat_v.ogm_wq,
+			   msecs_to_jiffies(msecs));
+}
+
+/**
+ * batadv_v_ogm_send_to_if - send a batman ogm using a given interface
+ * @skb: the OGM to send
+ * @hard_iface: the interface to use to send the OGM
+ */
+static void batadv_v_ogm_send_to_if(struct sk_buff *skb,
+				    struct batadv_hard_iface *hard_iface)
+{
+	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
+
+	if (hard_iface->if_status != BATADV_IF_ACTIVE)
+		return;
+
+	batadv_inc_counter(bat_priv, BATADV_CNT_MGMT_TX);
+	batadv_add_counter(bat_priv, BATADV_CNT_MGMT_TX_BYTES,
+			   skb->len + ETH_HLEN);
+
+	batadv_send_skb_packet(skb, hard_iface, batadv_broadcast_addr);
+}
+
+/**
+ * batadv_v_ogm_send - periodic worker broadcasting the own OGM
+ * @work: work queue item
+ */
+static void batadv_v_ogm_send(struct work_struct *work)
+{
+	struct batadv_hard_iface *hard_iface;
+	struct batadv_priv_bat_v *bat_v;
+	struct batadv_priv *bat_priv;
+	struct batadv_ogm2_packet *ogm_packet;
+	struct sk_buff *skb, *skb_tmp;
+	unsigned char *ogm_buff, *pkt_buff;
+	int ogm_buff_len;
+	u16 tvlv_len = 0;
+
+	bat_v = container_of(work, struct batadv_priv_bat_v, ogm_wq.work);
+	bat_priv = container_of(bat_v, struct batadv_priv, bat_v);
+
+	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING)
+		goto out;
+
+	ogm_buff = bat_priv->bat_v.ogm_buff;
+	ogm_buff_len = bat_priv->bat_v.ogm_buff_len;
+	/* tt changes have to be committed before the tvlv data is
+	 * appended as it may alter the tt tvlv container
+	 */
+	batadv_tt_local_commit_changes(bat_priv);
+	tvlv_len = batadv_tvlv_container_ogm_append(bat_priv, &ogm_buff,
+						    &ogm_buff_len,
+						    BATADV_OGM2_HLEN);
+
+	bat_priv->bat_v.ogm_buff = ogm_buff;
+	bat_priv->bat_v.ogm_buff_len = ogm_buff_len;
+
+	skb = netdev_alloc_skb_ip_align(NULL, ETH_HLEN + ogm_buff_len);
+	if (!skb)
+		goto reschedule;
+
+	skb_reserve(skb, ETH_HLEN);
+	pkt_buff = skb_put(skb, ogm_buff_len);
+	memcpy(pkt_buff, ogm_buff, ogm_buff_len);
+
+	ogm_packet = (struct batadv_ogm2_packet *)skb->data;
+	ogm_packet->seqno = htonl(atomic_read(&bat_priv->bat_v.ogm_seqno));
+	atomic_inc(&bat_priv->bat_v.ogm_seqno);
+	ogm_packet->tvlv_len = htons(tvlv_len);
+
+	/* broadcast on every interface */
+	rcu_read_lock();
+	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
+		if (hard_iface->soft_iface != bat_priv->soft_iface)
+			continue;
+
+		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+			   "Sending own OGM2 packet (originator %pM, seqno %u, throughput %u, TTL %d) on interface %s [%pM]\n",
+			   ogm_packet->orig, ntohl(ogm_packet->seqno),
+			   ntohl(ogm_packet->throughput), ogm_packet->ttl,
+			   hard_iface->net_dev->name,
+			   hard_iface->net_dev->dev_addr);
+
+		/* this skb gets consumed by batadv_v_ogm_send_to_if() */
+		skb_tmp = skb_clone(skb, GFP_ATOMIC);
+		if (!skb_tmp)
+			break;
+
+		batadv_v_ogm_send_to_if(skb_tmp, hard_iface);
+	}
+	rcu_read_unlock();
+
+	consume_skb(skb);
+
+reschedule:
+	batadv_v_ogm_start_timer(bat_priv);
+out:
+	return;
+}
+
+/**
+ * batadv_v_ogm_iface_enable - prepare an interface for B.A.T.M.A.N. V
+ * @hard_iface: the interface to prepare
+ *
+ * Takes care of scheduling own OGM sending routine for this interface.
+ *
+ * Return: 0 on success or a negative error code otherwise
+ */
+int batadv_v_ogm_iface_enable(struct batadv_hard_iface *hard_iface)
+{
+	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
+
+	batadv_v_ogm_start_timer(bat_priv);
+
+	return 0;
+}
+
+/**
+ * batadv_v_ogm_primary_iface_set - set a new primary interface
+ * @primary_iface: the new primary interface
+ */
+void batadv_v_ogm_primary_iface_set(struct batadv_hard_iface *primary_iface)
+{
+	struct batadv_priv *bat_priv = netdev_priv(primary_iface->soft_iface);
+	struct batadv_ogm2_packet *ogm_packet;
+
+	if (!bat_priv->bat_v.ogm_buff)
+		return;
+
+	ogm_packet = (struct batadv_ogm2_packet *)bat_priv->bat_v.ogm_buff;
+	ether_addr_copy(ogm_packet->orig, primary_iface->net_dev->dev_addr);
+}
+
+/**
+ * batadv_v_ogm_packet_recv - OGM2 receiving handler
+ * @skb: the received OGM
+ * @if_incoming: the interface where this OGM has been received
+ *
+ * Return: NET_RX_SUCCESS and consume the skb on success or returns NET_RX_DROP
+ * (without freeing the skb) on failure
+ */
+int batadv_v_ogm_packet_recv(struct sk_buff *skb,
+			     struct batadv_hard_iface *if_incoming)
+{
+	struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
+	struct batadv_ogm2_packet *ogm_packet;
+	struct ethhdr *ethhdr = eth_hdr(skb);
+
+	/* did we receive a OGM2 packet on an interface that does not have
+	 * B.A.T.M.A.N. V enabled ?
+	 */
+	if (strcmp(bat_priv->bat_algo_ops->name, "BATMAN_V") != 0)
+		return NET_RX_DROP;
+
+	if (!batadv_check_management_packet(skb, if_incoming, BATADV_OGM2_HLEN))
+		return NET_RX_DROP;
+
+	if (batadv_is_my_mac(bat_priv, ethhdr->h_source))
+		return NET_RX_DROP;
+
+	ogm_packet = (struct batadv_ogm2_packet *)skb->data;
+
+	if (batadv_is_my_mac(bat_priv, ogm_packet->orig))
+		return NET_RX_DROP;
+
+	batadv_inc_counter(bat_priv, BATADV_CNT_MGMT_RX);
+	batadv_add_counter(bat_priv, BATADV_CNT_MGMT_RX_BYTES,
+			   skb->len + ETH_HLEN);
+
+	consume_skb(skb);
+	return NET_RX_SUCCESS;
+}
+
+/**
+ * batadv_v_ogm_init - initialise the OGM2 engine
+ * @bat_priv: the bat priv with all the soft interface information
+ *
+ * Return: 0 on success or a negative error code in case of failure
+ */
+int batadv_v_ogm_init(struct batadv_priv *bat_priv)
+{
+	struct batadv_ogm2_packet *ogm_packet;
+	unsigned char *ogm_buff;
+	u32 random_seqno;
+
+	bat_priv->bat_v.ogm_buff_len = BATADV_OGM2_HLEN;
+	ogm_buff = kzalloc(bat_priv->bat_v.ogm_buff_len, GFP_ATOMIC);
+	if (!ogm_buff)
+		return -ENOMEM;
+
+	bat_priv->bat_v.ogm_buff = ogm_buff;
+	ogm_packet = (struct batadv_ogm2_packet *)ogm_buff;
+	ogm_packet->packet_type = BATADV_OGM2;
+	ogm_packet->version = BATADV_COMPAT_VERSION;
+	ogm_packet->ttl = BATADV_TTL;
+	ogm_packet->flags = BATADV_NO_FLAGS;
+	ogm_packet->throughput = htonl(BATADV_THROUGHPUT_MAX_VALUE);
+
+	/* randomize initial seqno to avoid collision */
+	get_random_bytes(&random_seqno, sizeof(random_seqno));
+	atomic_set(&bat_priv->bat_v.ogm_seqno, random_seqno);
+	INIT_DELAYED_WORK(&bat_priv->bat_v.ogm_wq, batadv_v_ogm_send);
+
+	return 0;
+}
+
+/**
+ * batadv_v_ogm_free - free OGM private resources
+ * @bat_priv: the bat priv with all the soft interface information
+ */
+void batadv_v_ogm_free(struct batadv_priv *bat_priv)
+{
+	cancel_delayed_work_sync(&bat_priv->bat_v.ogm_wq);
+
+	kfree(bat_priv->bat_v.ogm_buff);
+	bat_priv->bat_v.ogm_buff = NULL;
+	bat_priv->bat_v.ogm_buff_len = 0;
+}