The routing algorithm must be able to decide if a fragment can be merged with the missing part and still be passed to a forwarding interface. The fragments can only differ by one byte in case that the original payload had an uneven length. In that situation the sender has to inform all possible receivers that the tail is one byte longer using the flag UNI_FRAG_LARGETAIL. The combination of UNI_FRAG_LARGETAIL and UNI_FRAG_HEAD flag makes it possible to calculate the correct length for even and uneven sized payloads. The original formula missed to add the unicast header at all and forgot to remove the fragment header of the second fragment. This made the results highly unreliable and only useful for machines with large differences between the configured MTUs. Reported-by: Russell Senior <russell@personaltelco.net> Reported-by: Marek Lindner <lindner_marek@yahoo.de> Signed-off-by: Sven Eckelmann <sven@narfation.org>
350 lines
8.9 KiB
C
350 lines
8.9 KiB
C
/*
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* Copyright (C) 2010 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(struct unicast_packet),
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uni_diff = sizeof(struct unicast_frag_packet) - 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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skb_pull(tmp_skb, sizeof(struct unicast_frag_packet));
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if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0) {
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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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/* 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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}
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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(struct frag_packet_list_entry),
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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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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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spin_lock_bh(&bat_priv->orig_hash_lock);
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orig_node = ((struct orig_node *)
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hash_find(bat_priv->orig_hash, compare_orig, choose_orig,
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unicast_packet->orig));
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if (!orig_node) {
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pr_debug("couldn't find originator in orig_hash\n");
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goto out;
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}
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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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spin_unlock_bh(&bat_priv->orig_hash_lock);
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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 batman_if *batman_if, uint8_t dstaddr[])
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{
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struct unicast_packet tmp_uc, *unicast_packet;
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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(struct unicast_packet);
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int ucf_hdr_len = sizeof(struct unicast_frag_packet);
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int data_len = skb->len - uc_hdr_len;
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int large_tail = 0;
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if (!bat_priv->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(struct unicast_packet));
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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, bat_priv->primary_if->net_dev->dev_addr, ETH_ALEN);
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memcpy(frag2, frag1, sizeof(struct unicast_frag_packet));
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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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frag1->seqno = htons((uint16_t)atomic_inc_return(
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&batman_if->frag_seqno));
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frag2->seqno = htons((uint16_t)atomic_inc_return(
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&batman_if->frag_seqno));
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send_skb_packet(skb, batman_if, dstaddr);
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send_skb_packet(frag_skb, batman_if, dstaddr);
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return NET_RX_SUCCESS;
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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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return NET_RX_DROP;
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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 batman_if *batman_if;
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struct neigh_node *router;
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int data_len = skb->len;
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uint8_t dstaddr[6];
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spin_lock_bh(&bat_priv->orig_hash_lock);
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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 = (struct orig_node *)gw_get_selected(bat_priv);
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else
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orig_node = ((struct orig_node *)hash_find(bat_priv->orig_hash,
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compare_orig,
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choose_orig,
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ethhdr->h_dest));
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/* check for hna host */
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if (!orig_node)
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orig_node = transtable_search(bat_priv, ethhdr->h_dest);
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router = find_router(bat_priv, orig_node, NULL);
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if (!router)
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goto unlock;
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/* don't lock while sending the packets ... we therefore
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* copy the required data before sending */
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batman_if = router->if_incoming;
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memcpy(dstaddr, router->addr, ETH_ALEN);
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spin_unlock_bh(&bat_priv->orig_hash_lock);
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if (batman_if->if_status != IF_ACTIVE)
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goto dropped;
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if (my_skb_head_push(skb, sizeof(struct unicast_packet)) < 0)
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goto dropped;
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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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if (atomic_read(&bat_priv->fragmentation) &&
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data_len + sizeof(struct unicast_packet) >
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batman_if->net_dev->mtu) {
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/* send frag skb decreases ttl */
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unicast_packet->ttl++;
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return frag_send_skb(skb, bat_priv, batman_if,
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dstaddr);
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}
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send_skb_packet(skb, batman_if, dstaddr);
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return 0;
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unlock:
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spin_unlock_bh(&bat_priv->orig_hash_lock);
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dropped:
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kfree_skb(skb);
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return 1;
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}
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