net/batman-adv/unicast.c - maze/linux - Git at Google

 /* Copyright (C) 2010-2013 B.A.T.M.A.N. contributors:
  *
  * Andreas Langer
  *
  * 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, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  * 02110-1301, USA
  */

 #include "main.h"
 #include "unicast.h"
 #include "send.h"
 #include "soft-interface.h"
 #include "gateway_client.h"
 #include "originator.h"
 #include "hash.h"
 #include "translation-table.h"
 #include "routing.h"
 #include "hard-interface.h"


 static struct sk_buff *
 batadv_frag_merge_packet(struct list_head *head,
 			 struct batadv_frag_packet_list_entry *tfp,
 			 struct sk_buff *skb)
 {
 	struct batadv_unicast_frag_packet *up;
 	struct sk_buff *tmp_skb;
 	struct batadv_unicast_packet *unicast_packet;
 	int hdr_len = sizeof(*unicast_packet);
 	int uni_diff = sizeof(*up) - hdr_len;
 	uint8_t *packet_pos;

 	up = (struct batadv_unicast_frag_packet *)skb->data;
 	/* set skb to the first part and tmp_skb to the second part */
 	if (up->flags & BATADV_UNI_FRAG_HEAD) {
 		tmp_skb = tfp->skb;
 	} else {
 		tmp_skb = skb;
 		skb = tfp->skb;
 	}

 	if (skb_linearize(skb) < 0 || skb_linearize(tmp_skb) < 0)
 		goto err;

 	skb_pull(tmp_skb, sizeof(*up));
 	if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0)
 		goto err;

 	/* move free entry to end */
 	tfp->skb = NULL;
 	tfp->seqno = 0;
 	list_move_tail(&tfp->list, head);

 	memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
 	kfree_skb(tmp_skb);

 	memmove(skb->data + uni_diff, skb->data, hdr_len);
 	packet_pos = skb_pull(skb, uni_diff);
 	unicast_packet = (struct batadv_unicast_packet *)packet_pos;
 	unicast_packet->header.packet_type = BATADV_UNICAST;

 	return skb;

 err:
 	/* free buffered skb, skb will be freed later */
 	kfree_skb(tfp->skb);
 	return NULL;
 }

 static void batadv_frag_create_entry(struct list_head *head,
 				     struct sk_buff *skb)
 {
 	struct batadv_frag_packet_list_entry *tfp;
 	struct batadv_unicast_frag_packet *up;

 	up = (struct batadv_unicast_frag_packet *)skb->data;

 	/* free and oldest packets stand at the end */
 	tfp = list_entry((head)->prev, typeof(*tfp), list);
 	kfree_skb(tfp->skb);

 	tfp->seqno = ntohs(up->seqno);
 	tfp->skb = skb;
 	list_move(&tfp->list, head);
 	return;
 }

 static int batadv_frag_create_buffer(struct list_head *head)
 {
 	int i;
 	struct batadv_frag_packet_list_entry *tfp;

 	for (i = 0; i < BATADV_FRAG_BUFFER_SIZE; i++) {
 		tfp = kmalloc(sizeof(*tfp), GFP_ATOMIC);
 		if (!tfp) {
 			batadv_frag_list_free(head);
 			return -ENOMEM;
 		}
 		tfp->skb = NULL;
 		tfp->seqno = 0;
 		INIT_LIST_HEAD(&tfp->list);
 		list_add(&tfp->list, head);
 	}

 	return 0;
 }

 static struct batadv_frag_packet_list_entry *
 batadv_frag_search_packet(struct list_head *head,
 			  const struct batadv_unicast_frag_packet *up)
 {
 	struct batadv_frag_packet_list_entry *tfp;
 	struct batadv_unicast_frag_packet *tmp_up = NULL;
 	bool is_head_tmp, is_head;
 	uint16_t search_seqno;

 	if (up->flags & BATADV_UNI_FRAG_HEAD)
 		search_seqno = ntohs(up->seqno)+1;
 	else
 		search_seqno = ntohs(up->seqno)-1;

 	is_head = up->flags & BATADV_UNI_FRAG_HEAD;

 	list_for_each_entry(tfp, head, list) {
 		if (!tfp->skb)
 			continue;

 		if (tfp->seqno == ntohs(up->seqno))
 			goto mov_tail;

 		tmp_up = (struct batadv_unicast_frag_packet *)tfp->skb->data;

 		if (tfp->seqno == search_seqno) {
 			is_head_tmp = tmp_up->flags & BATADV_UNI_FRAG_HEAD;
 			if (is_head_tmp != is_head)
 				return tfp;
 			else
 				goto mov_tail;
 		}
 	}
 	return NULL;

 mov_tail:
 	list_move_tail(&tfp->list, head);
 	return NULL;
 }

 void batadv_frag_list_free(struct list_head *head)
 {
 	struct batadv_frag_packet_list_entry *pf, *tmp_pf;

 	if (!list_empty(head)) {
 		list_for_each_entry_safe(pf, tmp_pf, head, list) {
 			kfree_skb(pf->skb);
 			list_del(&pf->list);
 			kfree(pf);
 		}
 	}
 	return;
 }

 /* frag_reassemble_skb():
  * returns NET_RX_DROP if the operation failed - skb is left intact
  * returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
  * or the skb could be reassembled (skb_new will point to the new packet and
  * skb was freed)
  */
 int batadv_frag_reassemble_skb(struct sk_buff *skb,
 			       struct batadv_priv *bat_priv,
 			       struct sk_buff **new_skb)
 {
 	struct batadv_orig_node *orig_node;
 	struct batadv_frag_packet_list_entry *tmp_frag_entry;
 	int ret = NET_RX_DROP;
 	struct batadv_unicast_frag_packet *unicast_packet;

 	unicast_packet = (struct batadv_unicast_frag_packet *)skb->data;
 	*new_skb = NULL;

 	orig_node = batadv_orig_hash_find(bat_priv, unicast_packet->orig);
 	if (!orig_node)
 		goto out;

 	orig_node->last_frag_packet = jiffies;

 	if (list_empty(&orig_node->frag_list) &&
 	    batadv_frag_create_buffer(&orig_node->frag_list)) {
 		pr_debug("couldn't create frag buffer\n");
 		goto out;
 	}

 	tmp_frag_entry = batadv_frag_search_packet(&orig_node->frag_list,
 						   unicast_packet);

 	if (!tmp_frag_entry) {
 		batadv_frag_create_entry(&orig_node->frag_list, skb);
 		ret = NET_RX_SUCCESS;
 		goto out;
 	}

 	*new_skb = batadv_frag_merge_packet(&orig_node->frag_list,
 					    tmp_frag_entry, skb);
 	/* if not, merge failed */
 	if (*new_skb)
 		ret = NET_RX_SUCCESS;

 out:
 	if (orig_node)
 		batadv_orig_node_free_ref(orig_node);
 	return ret;
 }

 int batadv_frag_send_skb(struct sk_buff *skb, struct batadv_priv *bat_priv,
 			 struct batadv_hard_iface *hard_iface,
 			 const uint8_t dstaddr[])
 {
 	struct batadv_unicast_packet tmp_uc, *unicast_packet;
 	struct batadv_hard_iface *primary_if;
 	struct sk_buff *frag_skb;
 	struct batadv_unicast_frag_packet *frag1, *frag2;
 	int uc_hdr_len = sizeof(*unicast_packet);
 	int ucf_hdr_len = sizeof(*frag1);
 	int data_len = skb->len - uc_hdr_len;
 	int large_tail = 0, ret = NET_RX_DROP;
 	uint16_t seqno;

 	primary_if = batadv_primary_if_get_selected(bat_priv);
 	if (!primary_if)
 		goto dropped;

 	frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
 	if (!frag_skb)
 		goto dropped;
 	skb_reserve(frag_skb, ucf_hdr_len);

 	unicast_packet = (struct batadv_unicast_packet *)skb->data;
 	memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
 	skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);

 	if (batadv_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
 	    batadv_skb_head_push(frag_skb, ucf_hdr_len) < 0)
 		goto drop_frag;

 	frag1 = (struct batadv_unicast_frag_packet *)skb->data;
 	frag2 = (struct batadv_unicast_frag_packet *)frag_skb->data;

 	memcpy(frag1, &tmp_uc, sizeof(tmp_uc));

 	frag1->header.ttl--;
 	frag1->header.version = BATADV_COMPAT_VERSION;
 	frag1->header.packet_type = BATADV_UNICAST_FRAG;

 	memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 	memcpy(frag2, frag1, sizeof(*frag2));

 	if (data_len & 1)
 		large_tail = BATADV_UNI_FRAG_LARGETAIL;

 	frag1->flags = BATADV_UNI_FRAG_HEAD | large_tail;
 	frag2->flags = large_tail;

 	seqno = atomic_add_return(2, &hard_iface->frag_seqno);
 	frag1->seqno = htons(seqno - 1);
 	frag2->seqno = htons(seqno);

 	batadv_send_skb_packet(skb, hard_iface, dstaddr);
 	batadv_send_skb_packet(frag_skb, hard_iface, dstaddr);
 	ret = NET_RX_SUCCESS;
 	goto out;

 drop_frag:
 	kfree_skb(frag_skb);
 dropped:
 	kfree_skb(skb);
 out:
 	if (primary_if)
 		batadv_hardif_free_ref(primary_if);
 	return ret;
 }

 /**
  * batadv_unicast_push_and_fill_skb - extends the buffer and initializes the
  * common fields for unicast packets
  * @skb: packet
  * @hdr_size: amount of bytes to push at the beginning of the skb
  * @orig_node: the destination node
  *
  * Returns false if the buffer extension was not possible or true otherwise
  */
 static bool batadv_unicast_push_and_fill_skb(struct sk_buff *skb, int hdr_size,
 					     struct batadv_orig_node *orig_node)
 {
 	struct batadv_unicast_packet *unicast_packet;
 	uint8_t ttvn = (uint8_t)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->header.version = BATADV_COMPAT_VERSION;
 	/* batman packet type: unicast */
 	unicast_packet->header.packet_type = BATADV_UNICAST;
 	/* set unicast ttl */
 	unicast_packet->header.ttl = BATADV_TTL;
 	/* copy the destination for faster routing */
 	memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
 	/* set the destination tt version number */
 	unicast_packet->ttvn = ttvn;

 	return true;
 }

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

 /**
  * batadv_unicast_4addr_prepare_skb - encapsulate an skb with a unicast4addr
  * header
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the skb containing the payload to encapsulate
  * @orig_node: the destination node
  * @packet_subtype: the batman 4addr packet subtype to use
  *
  * Returns false if the payload could not be encapsulated or true otherwise
  */
 bool batadv_unicast_4addr_prepare_skb(struct batadv_priv *bat_priv,
 				      struct sk_buff *skb,
 				      struct batadv_orig_node *orig,
 				      int packet_subtype)
 {
 	struct batadv_hard_iface *primary_if;
 	struct batadv_unicast_4addr_packet *unicast_4addr_packet;
 	bool ret = false;

 	primary_if = batadv_primary_if_get_selected(bat_priv);
 	if (!primary_if)
 		goto out;

 	/* pull the header space and fill the unicast_packet substructure.
 	 * We can do that because the first member of the unicast_4addr_packet
 	 * is of type struct unicast_packet
 	 */
 	if (!batadv_unicast_push_and_fill_skb(skb,
 					      sizeof(*unicast_4addr_packet),
 					      orig))
 		goto out;

 	unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
 	unicast_4addr_packet->u.header.packet_type = BATADV_UNICAST_4ADDR;
 	memcpy(unicast_4addr_packet->src, primary_if->net_dev->dev_addr,
 	       ETH_ALEN);
 	unicast_4addr_packet->subtype = packet_subtype;
 	unicast_4addr_packet->reserved = 0;

 	ret = true;
 out:
 	if (primary_if)
 		batadv_hardif_free_ref(primary_if);
 	return ret;
 }

 /**
  * batadv_unicast_generic_send_skb - send an skb as unicast
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: payload to send
  * @packet_type: the batman unicast packet type to use
  * @packet_subtype: the batman packet subtype. It is ignored if packet_type is
  *		    not BATADV_UNICAT_4ADDR
  *
  * Returns 1 in case of error or 0 otherwise
  */
 int batadv_unicast_generic_send_skb(struct batadv_priv *bat_priv,
 				    struct sk_buff *skb, int packet_type,
 				    int packet_subtype)
 {
 	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 	struct batadv_unicast_packet *unicast_packet;
 	struct batadv_orig_node *orig_node;
 	struct batadv_neigh_node *neigh_node;
 	int data_len = skb->len;
 	int ret = NET_RX_DROP;
 	unsigned int dev_mtu;

 	/* get routing information */
 	if (is_multicast_ether_addr(ethhdr->h_dest)) {
 		orig_node = batadv_gw_get_selected_orig(bat_priv);
 		if (orig_node)
 			goto find_router;
 	}

 	/* check for tt host - increases orig_node refcount.
 	 * returns NULL in case of AP isolation
 	 */
 	orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 					     ethhdr->h_dest);

 find_router:
 	/* find_router():
 	 *  - if orig_node is NULL it returns NULL
 	 *  - increases neigh_nodes refcount if found.
 	 */
 	neigh_node = batadv_find_router(bat_priv, orig_node, NULL);

 	if (!neigh_node)
 		goto out;

 	switch (packet_type) {
 	case BATADV_UNICAST:
 		batadv_unicast_prepare_skb(skb, orig_node);
 		break;
 	case BATADV_UNICAST_4ADDR:
 		batadv_unicast_4addr_prepare_skb(bat_priv, skb, orig_node,
 						 packet_subtype);
 		break;
 	default:
 		/* this function supports UNICAST and UNICAST_4ADDR only. It
 		 * should never be invoked with any other packet type
 		 */
 		goto out;
 	}

 	unicast_packet = (struct batadv_unicast_packet *)skb->data;

 	/* inform the destination node that we are still missing a correct route
 	 * for this client. The destination will receive this packet and will
 	 * try to reroute it because the ttvn contained in the header is less
 	 * than the current one
 	 */
 	if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest))
 		unicast_packet->ttvn = unicast_packet->ttvn - 1;

 	dev_mtu = neigh_node->if_incoming->net_dev->mtu;
 	/* fragmentation mechanism only works for UNICAST (now) */
 	if (packet_type == BATADV_UNICAST &&
 	    atomic_read(&bat_priv->fragmentation) &&
 	    data_len + sizeof(*unicast_packet) > dev_mtu) {
 		/* send frag skb decreases ttl */
 		unicast_packet->header.ttl++;
 		ret = batadv_frag_send_skb(skb, bat_priv,
 					   neigh_node->if_incoming,
 					   neigh_node->addr);
 		goto out;
 	}

 	if (batadv_send_skb_to_orig(skb, orig_node, NULL))
 		ret = 0;

 out:
 	if (neigh_node)
 		batadv_neigh_node_free_ref(neigh_node);
 	if (orig_node)
 		batadv_orig_node_free_ref(orig_node);
 	if (ret == NET_RX_DROP)
 		kfree_skb(skb);
 	return ret;
 }
	/* Copyright (C) 2010-2013 B.A.T.M.A.N. contributors:
	*
	* Andreas Langer
	*
	* 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, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
	* 02110-1301, USA
	*/

	#include "main.h"
	#include "unicast.h"
	#include "send.h"
	#include "soft-interface.h"
	#include "gateway_client.h"
	#include "originator.h"
	#include "hash.h"
	#include "translation-table.h"
	#include "routing.h"
	#include "hard-interface.h"


	static struct sk_buff *
	batadv_frag_merge_packet(struct list_head *head,
	struct batadv_frag_packet_list_entry *tfp,
	struct sk_buff *skb)
	{
	struct batadv_unicast_frag_packet *up;
	struct sk_buff *tmp_skb;
	struct batadv_unicast_packet *unicast_packet;
	int hdr_len = sizeof(*unicast_packet);
	int uni_diff = sizeof(*up) - hdr_len;
	uint8_t *packet_pos;

	up = (struct batadv_unicast_frag_packet *)skb->data;
	/* set skb to the first part and tmp_skb to the second part */
	if (up->flags & BATADV_UNI_FRAG_HEAD) {
	tmp_skb = tfp->skb;
	} else {
	tmp_skb = skb;
	skb = tfp->skb;
	}

	if (skb_linearize(skb) < 0 \|\| skb_linearize(tmp_skb) < 0)
	goto err;

	skb_pull(tmp_skb, sizeof(*up));
	if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0)
	goto err;

	/* move free entry to end */
	tfp->skb = NULL;
	tfp->seqno = 0;
	list_move_tail(&tfp->list, head);

	memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
	kfree_skb(tmp_skb);

	memmove(skb->data + uni_diff, skb->data, hdr_len);
	packet_pos = skb_pull(skb, uni_diff);
	unicast_packet = (struct batadv_unicast_packet *)packet_pos;
	unicast_packet->header.packet_type = BATADV_UNICAST;

	return skb;

	err:
	/* free buffered skb, skb will be freed later */
	kfree_skb(tfp->skb);
	return NULL;
	}

	static void batadv_frag_create_entry(struct list_head *head,
	struct sk_buff *skb)
	{
	struct batadv_frag_packet_list_entry *tfp;
	struct batadv_unicast_frag_packet *up;

	up = (struct batadv_unicast_frag_packet *)skb->data;

	/* free and oldest packets stand at the end */
	tfp = list_entry((head)->prev, typeof(*tfp), list);
	kfree_skb(tfp->skb);

	tfp->seqno = ntohs(up->seqno);
	tfp->skb = skb;
	list_move(&tfp->list, head);
	return;
	}

	static int batadv_frag_create_buffer(struct list_head *head)
	{
	int i;
	struct batadv_frag_packet_list_entry *tfp;

	for (i = 0; i < BATADV_FRAG_BUFFER_SIZE; i++) {
	tfp = kmalloc(sizeof(*tfp), GFP_ATOMIC);
	if (!tfp) {
	batadv_frag_list_free(head);
	return -ENOMEM;
	}
	tfp->skb = NULL;
	tfp->seqno = 0;
	INIT_LIST_HEAD(&tfp->list);
	list_add(&tfp->list, head);
	}

	return 0;
	}

	static struct batadv_frag_packet_list_entry *
	batadv_frag_search_packet(struct list_head *head,
	const struct batadv_unicast_frag_packet *up)
	{
	struct batadv_frag_packet_list_entry *tfp;
	struct batadv_unicast_frag_packet *tmp_up = NULL;
	bool is_head_tmp, is_head;
	uint16_t search_seqno;

	if (up->flags & BATADV_UNI_FRAG_HEAD)
	search_seqno = ntohs(up->seqno)+1;
	else
	search_seqno = ntohs(up->seqno)-1;

	is_head = up->flags & BATADV_UNI_FRAG_HEAD;

	list_for_each_entry(tfp, head, list) {
	if (!tfp->skb)
	continue;

	if (tfp->seqno == ntohs(up->seqno))
	goto mov_tail;

	tmp_up = (struct batadv_unicast_frag_packet *)tfp->skb->data;

	if (tfp->seqno == search_seqno) {
	is_head_tmp = tmp_up->flags & BATADV_UNI_FRAG_HEAD;
	if (is_head_tmp != is_head)
	return tfp;
	else
	goto mov_tail;
	}
	}
	return NULL;

	mov_tail:
	list_move_tail(&tfp->list, head);
	return NULL;
	}

	void batadv_frag_list_free(struct list_head *head)
	{
	struct batadv_frag_packet_list_entry pf, tmp_pf;

	if (!list_empty(head)) {
	list_for_each_entry_safe(pf, tmp_pf, head, list) {
	kfree_skb(pf->skb);
	list_del(&pf->list);
	kfree(pf);
	}
	}
	return;
	}

	/* frag_reassemble_skb():
	* returns NET_RX_DROP if the operation failed - skb is left intact
	* returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
	* or the skb could be reassembled (skb_new will point to the new packet and
	* skb was freed)
	*/
	int batadv_frag_reassemble_skb(struct sk_buff *skb,
	struct batadv_priv *bat_priv,
	struct sk_buff **new_skb)
	{
	struct batadv_orig_node *orig_node;
	struct batadv_frag_packet_list_entry *tmp_frag_entry;
	int ret = NET_RX_DROP;
	struct batadv_unicast_frag_packet *unicast_packet;

	unicast_packet = (struct batadv_unicast_frag_packet *)skb->data;
	*new_skb = NULL;

	orig_node = batadv_orig_hash_find(bat_priv, unicast_packet->orig);
	if (!orig_node)
	goto out;

	orig_node->last_frag_packet = jiffies;

	if (list_empty(&orig_node->frag_list) &&
	batadv_frag_create_buffer(&orig_node->frag_list)) {
	pr_debug("couldn't create frag buffer\n");
	goto out;
	}

	tmp_frag_entry = batadv_frag_search_packet(&orig_node->frag_list,
	unicast_packet);

	if (!tmp_frag_entry) {
	batadv_frag_create_entry(&orig_node->frag_list, skb);
	ret = NET_RX_SUCCESS;
	goto out;
	}

	*new_skb = batadv_frag_merge_packet(&orig_node->frag_list,
	tmp_frag_entry, skb);
	/* if not, merge failed */
	if (*new_skb)
	ret = NET_RX_SUCCESS;

	out:
	if (orig_node)
	batadv_orig_node_free_ref(orig_node);
	return ret;
	}

	int batadv_frag_send_skb(struct sk_buff skb, struct batadv_priv bat_priv,
	struct batadv_hard_iface *hard_iface,
	const uint8_t dstaddr[])
	{
	struct batadv_unicast_packet tmp_uc, *unicast_packet;
	struct batadv_hard_iface *primary_if;
	struct sk_buff *frag_skb;
	struct batadv_unicast_frag_packet frag1, frag2;
	int uc_hdr_len = sizeof(*unicast_packet);
	int ucf_hdr_len = sizeof(*frag1);
	int data_len = skb->len - uc_hdr_len;
	int large_tail = 0, ret = NET_RX_DROP;
	uint16_t seqno;

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if)
	goto dropped;

	frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
	if (!frag_skb)
	goto dropped;
	skb_reserve(frag_skb, ucf_hdr_len);

	unicast_packet = (struct batadv_unicast_packet *)skb->data;
	memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
	skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);

	if (batadv_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 \|\|
	batadv_skb_head_push(frag_skb, ucf_hdr_len) < 0)
	goto drop_frag;

	frag1 = (struct batadv_unicast_frag_packet *)skb->data;
	frag2 = (struct batadv_unicast_frag_packet *)frag_skb->data;

	memcpy(frag1, &tmp_uc, sizeof(tmp_uc));

	frag1->header.ttl--;
	frag1->header.version = BATADV_COMPAT_VERSION;
	frag1->header.packet_type = BATADV_UNICAST_FRAG;

	memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
	memcpy(frag2, frag1, sizeof(*frag2));

	if (data_len & 1)
	large_tail = BATADV_UNI_FRAG_LARGETAIL;

	frag1->flags = BATADV_UNI_FRAG_HEAD \| large_tail;
	frag2->flags = large_tail;

	seqno = atomic_add_return(2, &hard_iface->frag_seqno);
	frag1->seqno = htons(seqno - 1);
	frag2->seqno = htons(seqno);

	batadv_send_skb_packet(skb, hard_iface, dstaddr);
	batadv_send_skb_packet(frag_skb, hard_iface, dstaddr);
	ret = NET_RX_SUCCESS;
	goto out;

	drop_frag:
	kfree_skb(frag_skb);
	dropped:
	kfree_skb(skb);
	out:
	if (primary_if)
	batadv_hardif_free_ref(primary_if);
	return ret;
	}

	/**
	* batadv_unicast_push_and_fill_skb - extends the buffer and initializes the
	* common fields for unicast packets
	* @skb: packet
	* @hdr_size: amount of bytes to push at the beginning of the skb
	* @orig_node: the destination node
	*
	* Returns false if the buffer extension was not possible or true otherwise
	*/
	static bool batadv_unicast_push_and_fill_skb(struct sk_buff *skb, int hdr_size,
	struct batadv_orig_node *orig_node)
	{
	struct batadv_unicast_packet *unicast_packet;
	uint8_t ttvn = (uint8_t)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->header.version = BATADV_COMPAT_VERSION;
	/* batman packet type: unicast */
	unicast_packet->header.packet_type = BATADV_UNICAST;
	/* set unicast ttl */
	unicast_packet->header.ttl = BATADV_TTL;
	/* copy the destination for faster routing */
	memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
	/* set the destination tt version number */
	unicast_packet->ttvn = ttvn;

	return true;
	}

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

	/**
	* batadv_unicast_4addr_prepare_skb - encapsulate an skb with a unicast4addr
	* header
	* @bat_priv: the bat priv with all the soft interface information
	* @skb: the skb containing the payload to encapsulate
	* @orig_node: the destination node
	* @packet_subtype: the batman 4addr packet subtype to use
	*
	* Returns false if the payload could not be encapsulated or true otherwise
	*/
	bool batadv_unicast_4addr_prepare_skb(struct batadv_priv *bat_priv,
	struct sk_buff *skb,
	struct batadv_orig_node *orig,
	int packet_subtype)
	{
	struct batadv_hard_iface *primary_if;
	struct batadv_unicast_4addr_packet *unicast_4addr_packet;
	bool ret = false;

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if)
	goto out;

	/* pull the header space and fill the unicast_packet substructure.
	* We can do that because the first member of the unicast_4addr_packet
	* is of type struct unicast_packet
	*/
	if (!batadv_unicast_push_and_fill_skb(skb,
	sizeof(*unicast_4addr_packet),
	orig))
	goto out;

	unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
	unicast_4addr_packet->u.header.packet_type = BATADV_UNICAST_4ADDR;
	memcpy(unicast_4addr_packet->src, primary_if->net_dev->dev_addr,
	ETH_ALEN);
	unicast_4addr_packet->subtype = packet_subtype;
	unicast_4addr_packet->reserved = 0;

	ret = true;
	out:
	if (primary_if)
	batadv_hardif_free_ref(primary_if);
	return ret;
	}

	/**
	* batadv_unicast_generic_send_skb - send an skb as unicast
	* @bat_priv: the bat priv with all the soft interface information
	* @skb: payload to send
	* @packet_type: the batman unicast packet type to use
	* @packet_subtype: the batman packet subtype. It is ignored if packet_type is
	* not BATADV_UNICAT_4ADDR
	*
	* Returns 1 in case of error or 0 otherwise
	*/
	int batadv_unicast_generic_send_skb(struct batadv_priv *bat_priv,
	struct sk_buff *skb, int packet_type,
	int packet_subtype)
	{
	struct ethhdr ethhdr = (struct ethhdr )skb->data;
	struct batadv_unicast_packet *unicast_packet;
	struct batadv_orig_node *orig_node;
	struct batadv_neigh_node *neigh_node;
	int data_len = skb->len;
	int ret = NET_RX_DROP;
	unsigned int dev_mtu;

	/* get routing information */
	if (is_multicast_ether_addr(ethhdr->h_dest)) {
	orig_node = batadv_gw_get_selected_orig(bat_priv);
	if (orig_node)
	goto find_router;
	}

	/* check for tt host - increases orig_node refcount.
	* returns NULL in case of AP isolation
	*/
	orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
	ethhdr->h_dest);

	find_router:
	/* find_router():
	* - if orig_node is NULL it returns NULL
	* - increases neigh_nodes refcount if found.
	*/
	neigh_node = batadv_find_router(bat_priv, orig_node, NULL);

	if (!neigh_node)
	goto out;

	switch (packet_type) {
	case BATADV_UNICAST:
	batadv_unicast_prepare_skb(skb, orig_node);
	break;
	case BATADV_UNICAST_4ADDR:
	batadv_unicast_4addr_prepare_skb(bat_priv, skb, orig_node,
	packet_subtype);
	break;
	default:
	/* this function supports UNICAST and UNICAST_4ADDR only. It
	* should never be invoked with any other packet type
	*/
	goto out;
	}

	unicast_packet = (struct batadv_unicast_packet *)skb->data;

	/* inform the destination node that we are still missing a correct route
	* for this client. The destination will receive this packet and will
	* try to reroute it because the ttvn contained in the header is less
	* than the current one
	*/
	if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest))
	unicast_packet->ttvn = unicast_packet->ttvn - 1;

	dev_mtu = neigh_node->if_incoming->net_dev->mtu;
	/* fragmentation mechanism only works for UNICAST (now) */
	if (packet_type == BATADV_UNICAST &&
	atomic_read(&bat_priv->fragmentation) &&
	data_len + sizeof(*unicast_packet) > dev_mtu) {
	/* send frag skb decreases ttl */
	unicast_packet->header.ttl++;
	ret = batadv_frag_send_skb(skb, bat_priv,
	neigh_node->if_incoming,
	neigh_node->addr);
	goto out;
	}

	if (batadv_send_skb_to_orig(skb, orig_node, NULL))
	ret = 0;

	out:
	if (neigh_node)
	batadv_neigh_node_free_ref(neigh_node);
	if (orig_node)
	batadv_orig_node_free_ref(orig_node);
	if (ret == NET_RX_DROP)
	kfree_skb(skb);
	return ret;
	}