![Antonio Quartulli](/assets/img/avatar_default.png)
The client announcement mechanism informs every mesh node in the network of any connected non-mesh client, in order to find the path towards that client from any given point in the mesh. The old implementation was based on the simple idea of appending a data buffer to each OGM containing all the client MAC addresses the node is serving. All other nodes can populate their global translation tables (table which links client MAC addresses to node addresses) using this MAC address buffer and linking it to the node's address contained in the OGM. A node that wants to contact a client has to lookup the node the client is connected to and its address in the global translation table. It is easy to understand that this implementation suffers from several issues: - big overhead (each and every OGM contains the entire list of connected clients) - high latencies for client route updates due to long OGM trip time and OGM losses The new implementation addresses these issues by appending client changes (new client joined or a client left) to the OGM instead of filling it with all the client addresses each time. In this way nodes can modify their global tables by means of "updates", thus reducing the overhead within the OGMs. To keep the entire network in sync each node maintains a translation table version number (ttvn) and a translation table checksum. These values are spread with the OGM to allow all the network participants to determine whether or not they need to update their translation table information. When a translation table lookup is performed in order to send a packet to a client attached to another node, the destination's ttvn is added to the payload packet. Forwarding nodes can compare the packet's ttvn with their destination's ttvn (this node could have a fresher information than the source) and re-route the packet if necessary. This greatly reduces the packet loss of clients roaming from one AP to the next. Signed-off-by: Antonio Quartulli <ordex@autistici.org> Signed-off-by: Marek Lindner <lindner_marek@yahoo.de> Signed-off-by: Sven Eckelmann <sven@narfation.org>
355 lines
8.7 KiB
C
355 lines
8.7 KiB
C
/*
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* Copyright (C) 2010-2011 B.A.T.M.A.N. contributors:
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*
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* Andreas Langer
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA
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*
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*/
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#include "main.h"
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#include "unicast.h"
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#include "send.h"
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#include "soft-interface.h"
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#include "gateway_client.h"
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#include "originator.h"
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#include "hash.h"
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#include "translation-table.h"
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#include "routing.h"
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#include "hard-interface.h"
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static struct sk_buff *frag_merge_packet(struct list_head *head,
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struct frag_packet_list_entry *tfp,
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struct sk_buff *skb)
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{
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struct unicast_frag_packet *up =
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(struct unicast_frag_packet *)skb->data;
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struct sk_buff *tmp_skb;
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struct unicast_packet *unicast_packet;
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int hdr_len = sizeof(*unicast_packet);
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int uni_diff = sizeof(*up) - hdr_len;
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/* set skb to the first part and tmp_skb to the second part */
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if (up->flags & UNI_FRAG_HEAD) {
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tmp_skb = tfp->skb;
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} else {
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tmp_skb = skb;
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skb = tfp->skb;
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}
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if (skb_linearize(skb) < 0 || skb_linearize(tmp_skb) < 0)
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goto err;
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skb_pull(tmp_skb, sizeof(*up));
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if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0)
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goto err;
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/* move free entry to end */
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tfp->skb = NULL;
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tfp->seqno = 0;
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list_move_tail(&tfp->list, head);
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memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
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kfree_skb(tmp_skb);
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memmove(skb->data + uni_diff, skb->data, hdr_len);
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unicast_packet = (struct unicast_packet *) skb_pull(skb, uni_diff);
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unicast_packet->packet_type = BAT_UNICAST;
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return skb;
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err:
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/* free buffered skb, skb will be freed later */
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kfree_skb(tfp->skb);
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return NULL;
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}
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static void frag_create_entry(struct list_head *head, struct sk_buff *skb)
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{
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struct frag_packet_list_entry *tfp;
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struct unicast_frag_packet *up =
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(struct unicast_frag_packet *)skb->data;
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/* free and oldest packets stand at the end */
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tfp = list_entry((head)->prev, typeof(*tfp), list);
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kfree_skb(tfp->skb);
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tfp->seqno = ntohs(up->seqno);
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tfp->skb = skb;
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list_move(&tfp->list, head);
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return;
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}
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static int frag_create_buffer(struct list_head *head)
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{
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int i;
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struct frag_packet_list_entry *tfp;
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for (i = 0; i < FRAG_BUFFER_SIZE; i++) {
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tfp = kmalloc(sizeof(*tfp), GFP_ATOMIC);
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if (!tfp) {
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frag_list_free(head);
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return -ENOMEM;
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}
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tfp->skb = NULL;
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tfp->seqno = 0;
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INIT_LIST_HEAD(&tfp->list);
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list_add(&tfp->list, head);
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}
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return 0;
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}
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static struct frag_packet_list_entry *frag_search_packet(struct list_head *head,
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const struct unicast_frag_packet *up)
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{
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struct frag_packet_list_entry *tfp;
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struct unicast_frag_packet *tmp_up = NULL;
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uint16_t search_seqno;
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if (up->flags & UNI_FRAG_HEAD)
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search_seqno = ntohs(up->seqno)+1;
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else
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search_seqno = ntohs(up->seqno)-1;
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list_for_each_entry(tfp, head, list) {
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if (!tfp->skb)
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continue;
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if (tfp->seqno == ntohs(up->seqno))
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goto mov_tail;
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tmp_up = (struct unicast_frag_packet *)tfp->skb->data;
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if (tfp->seqno == search_seqno) {
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if ((tmp_up->flags & UNI_FRAG_HEAD) !=
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(up->flags & UNI_FRAG_HEAD))
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return tfp;
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else
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goto mov_tail;
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}
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}
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return NULL;
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mov_tail:
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list_move_tail(&tfp->list, head);
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return NULL;
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}
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void frag_list_free(struct list_head *head)
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{
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struct frag_packet_list_entry *pf, *tmp_pf;
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if (!list_empty(head)) {
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list_for_each_entry_safe(pf, tmp_pf, head, list) {
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kfree_skb(pf->skb);
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list_del(&pf->list);
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kfree(pf);
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}
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}
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return;
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}
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/* frag_reassemble_skb():
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* returns NET_RX_DROP if the operation failed - skb is left intact
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* returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
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* or the skb could be reassembled (skb_new will point to the new packet and
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* skb was freed)
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*/
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int frag_reassemble_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
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struct sk_buff **new_skb)
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{
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struct orig_node *orig_node;
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struct frag_packet_list_entry *tmp_frag_entry;
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int ret = NET_RX_DROP;
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struct unicast_frag_packet *unicast_packet =
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(struct unicast_frag_packet *)skb->data;
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*new_skb = NULL;
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orig_node = orig_hash_find(bat_priv, unicast_packet->orig);
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if (!orig_node)
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goto out;
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orig_node->last_frag_packet = jiffies;
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if (list_empty(&orig_node->frag_list) &&
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frag_create_buffer(&orig_node->frag_list)) {
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pr_debug("couldn't create frag buffer\n");
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goto out;
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}
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tmp_frag_entry = frag_search_packet(&orig_node->frag_list,
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unicast_packet);
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if (!tmp_frag_entry) {
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frag_create_entry(&orig_node->frag_list, skb);
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ret = NET_RX_SUCCESS;
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goto out;
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}
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*new_skb = frag_merge_packet(&orig_node->frag_list, tmp_frag_entry,
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skb);
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/* if not, merge failed */
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if (*new_skb)
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ret = NET_RX_SUCCESS;
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out:
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if (orig_node)
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orig_node_free_ref(orig_node);
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return ret;
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}
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int frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
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struct hard_iface *hard_iface, const uint8_t dstaddr[])
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{
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struct unicast_packet tmp_uc, *unicast_packet;
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struct hard_iface *primary_if;
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struct sk_buff *frag_skb;
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struct unicast_frag_packet *frag1, *frag2;
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int uc_hdr_len = sizeof(*unicast_packet);
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int ucf_hdr_len = sizeof(*frag1);
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int data_len = skb->len - uc_hdr_len;
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int large_tail = 0, ret = NET_RX_DROP;
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uint16_t seqno;
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primary_if = primary_if_get_selected(bat_priv);
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if (!primary_if)
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goto dropped;
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frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
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if (!frag_skb)
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goto dropped;
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skb_reserve(frag_skb, ucf_hdr_len);
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unicast_packet = (struct unicast_packet *) skb->data;
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memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
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skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
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if (my_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
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my_skb_head_push(frag_skb, ucf_hdr_len) < 0)
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goto drop_frag;
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frag1 = (struct unicast_frag_packet *)skb->data;
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frag2 = (struct unicast_frag_packet *)frag_skb->data;
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memcpy(frag1, &tmp_uc, sizeof(tmp_uc));
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frag1->ttl--;
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frag1->version = COMPAT_VERSION;
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frag1->packet_type = BAT_UNICAST_FRAG;
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memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
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memcpy(frag2, frag1, sizeof(*frag2));
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if (data_len & 1)
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large_tail = UNI_FRAG_LARGETAIL;
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frag1->flags = UNI_FRAG_HEAD | large_tail;
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frag2->flags = large_tail;
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seqno = atomic_add_return(2, &hard_iface->frag_seqno);
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frag1->seqno = htons(seqno - 1);
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frag2->seqno = htons(seqno);
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send_skb_packet(skb, hard_iface, dstaddr);
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send_skb_packet(frag_skb, hard_iface, dstaddr);
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ret = NET_RX_SUCCESS;
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goto out;
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drop_frag:
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kfree_skb(frag_skb);
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dropped:
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kfree_skb(skb);
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out:
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if (primary_if)
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hardif_free_ref(primary_if);
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return ret;
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}
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int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
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{
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struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
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struct unicast_packet *unicast_packet;
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struct orig_node *orig_node;
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struct neigh_node *neigh_node;
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int data_len = skb->len;
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int ret = 1;
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/* get routing information */
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if (is_multicast_ether_addr(ethhdr->h_dest)) {
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orig_node = gw_get_selected_orig(bat_priv);
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if (orig_node)
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goto find_router;
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}
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/* check for tt host - increases orig_node refcount */
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orig_node = transtable_search(bat_priv, ethhdr->h_dest);
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find_router:
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/**
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* find_router():
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* - if orig_node is NULL it returns NULL
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* - increases neigh_nodes refcount if found.
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*/
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neigh_node = find_router(bat_priv, orig_node, NULL);
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if (!neigh_node)
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goto out;
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if (my_skb_head_push(skb, sizeof(*unicast_packet)) < 0)
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goto out;
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unicast_packet = (struct unicast_packet *)skb->data;
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unicast_packet->version = COMPAT_VERSION;
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/* batman packet type: unicast */
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unicast_packet->packet_type = BAT_UNICAST;
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/* set unicast ttl */
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unicast_packet->ttl = TTL;
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/* copy the destination for faster routing */
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memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
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/* set the destination tt version number */
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unicast_packet->ttvn =
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(uint8_t)atomic_read(&orig_node->last_ttvn);
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if (atomic_read(&bat_priv->fragmentation) &&
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data_len + sizeof(*unicast_packet) >
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neigh_node->if_incoming->net_dev->mtu) {
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/* send frag skb decreases ttl */
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unicast_packet->ttl++;
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ret = frag_send_skb(skb, bat_priv,
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neigh_node->if_incoming, neigh_node->addr);
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goto out;
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}
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send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
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ret = 0;
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goto out;
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out:
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if (neigh_node)
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neigh_node_free_ref(neigh_node);
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if (orig_node)
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orig_node_free_ref(orig_node);
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if (ret == 1)
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kfree_skb(skb);
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return ret;
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}
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