net/batman-adv/unicast.c

   1 /*
   2  * Copyright (C) 2010-2011 B.A.T.M.A.N. contributors:
   3  *
   4  * Andreas Langer
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of version 2 of the GNU General Public
   8  * License as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA
  19  *
  20  */
  21
  22 #include "main.h"
  23 #include "unicast.h"
  24 #include "send.h"
  25 #include "soft-interface.h"
  26 #include "gateway_client.h"
  27 #include "originator.h"
  28 #include "hash.h"
  29 #include "translation-table.h"
  30 #include "routing.h"
  31 #include "hard-interface.h"
  32
  33
  34 static struct sk_buff *frag_merge_packet(struct list_head *head,
  35                                          struct frag_packet_list_entry *tfp,
  36                                          struct sk_buff *skb)
  37 {
  38         struct unicast_frag_packet *up =
  39                 (struct unicast_frag_packet *)skb->data;
  40         struct sk_buff *tmp_skb;
  41         struct unicast_packet *unicast_packet;
  42         int hdr_len = sizeof(struct unicast_packet);
  43         int uni_diff = sizeof(struct unicast_frag_packet) - hdr_len;
  44
  45         /* set skb to the first part and tmp_skb to the second part */
  46         if (up->flags & UNI_FRAG_HEAD) {
  47                 tmp_skb = tfp->skb;
  48         } else {
  49                 tmp_skb = skb;
  50                 skb = tfp->skb;
  51         }
  52
  53         if (skb_linearize(skb) < 0 || skb_linearize(tmp_skb) < 0)
  54                 goto err;
  55
  56         skb_pull(tmp_skb, sizeof(struct unicast_frag_packet));
  57         if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0)
  58                 goto err;
  59
  60         /* move free entry to end */
  61         tfp->skb = NULL;
  62         tfp->seqno = 0;
  63         list_move_tail(&tfp->list, head);
  64
  65         memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
  66         kfree_skb(tmp_skb);
  67
  68         memmove(skb->data + uni_diff, skb->data, hdr_len);
  69         unicast_packet = (struct unicast_packet *) skb_pull(skb, uni_diff);
  70         unicast_packet->packet_type = BAT_UNICAST;
  71
  72         return skb;
  73
  74 err:
  75         /* free buffered skb, skb will be freed later */
  76         kfree_skb(tfp->skb);
  77         return NULL;
  78 }
  79
  80 static void frag_create_entry(struct list_head *head, struct sk_buff *skb)
  81 {
  82         struct frag_packet_list_entry *tfp;
  83         struct unicast_frag_packet *up =
  84                 (struct unicast_frag_packet *)skb->data;
  85
  86         /* free and oldest packets stand at the end */
  87         tfp = list_entry((head)->prev, typeof(*tfp), list);
  88         kfree_skb(tfp->skb);
  89
  90         tfp->seqno = ntohs(up->seqno);
  91         tfp->skb = skb;
  92         list_move(&tfp->list, head);
  93         return;
  94 }
  95
  96 static int frag_create_buffer(struct list_head *head)
  97 {
  98         int i;
  99         struct frag_packet_list_entry *tfp;
 100
 101         for (i = 0; i < FRAG_BUFFER_SIZE; i++) {
 102                 tfp = kmalloc(sizeof(struct frag_packet_list_entry),
 103                         GFP_ATOMIC);
 104                 if (!tfp) {
 105                         frag_list_free(head);
 106                         return -ENOMEM;
 107                 }
 108                 tfp->skb = NULL;
 109                 tfp->seqno = 0;
 110                 INIT_LIST_HEAD(&tfp->list);
 111                 list_add(&tfp->list, head);
 112         }
 113
 114         return 0;
 115 }
 116
 117 static struct frag_packet_list_entry *frag_search_packet(struct list_head *head,
 118                                                  struct unicast_frag_packet *up)
 119 {
 120         struct frag_packet_list_entry *tfp;
 121         struct unicast_frag_packet *tmp_up = NULL;
 122         uint16_t search_seqno;
 123
 124         if (up->flags & UNI_FRAG_HEAD)
 125                 search_seqno = ntohs(up->seqno)+1;
 126         else
 127                 search_seqno = ntohs(up->seqno)-1;
 128
 129         list_for_each_entry(tfp, head, list) {
 130
 131                 if (!tfp->skb)
 132                         continue;
 133
 134                 if (tfp->seqno == ntohs(up->seqno))
 135                         goto mov_tail;
 136
 137                 tmp_up = (struct unicast_frag_packet *)tfp->skb->data;
 138
 139                 if (tfp->seqno == search_seqno) {
 140
 141                         if ((tmp_up->flags & UNI_FRAG_HEAD) !=
 142                             (up->flags & UNI_FRAG_HEAD))
 143                                 return tfp;
 144                         else
 145                                 goto mov_tail;
 146                 }
 147         }
 148         return NULL;
 149
 150 mov_tail:
 151         list_move_tail(&tfp->list, head);
 152         return NULL;
 153 }
 154
 155 void frag_list_free(struct list_head *head)
 156 {
 157         struct frag_packet_list_entry *pf, *tmp_pf;
 158
 159         if (!list_empty(head)) {
 160
 161                 list_for_each_entry_safe(pf, tmp_pf, head, list) {
 162                         kfree_skb(pf->skb);
 163                         list_del(&pf->list);
 164                         kfree(pf);
 165                 }
 166         }
 167         return;
 168 }
 169
 170 /* frag_reassemble_skb():
 171  * returns NET_RX_DROP if the operation failed - skb is left intact
 172  * returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
 173  * or the skb could be reassembled (skb_new will point to the new packet and
 174  * skb was freed)
 175  */
 176 int frag_reassemble_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
 177                         struct sk_buff **new_skb)
 178 {
 179         struct orig_node *orig_node;
 180         struct frag_packet_list_entry *tmp_frag_entry;
 181         int ret = NET_RX_DROP;
 182         struct unicast_frag_packet *unicast_packet =
 183                 (struct unicast_frag_packet *)skb->data;
 184
 185         *new_skb = NULL;
 186
 187         orig_node = orig_hash_find(bat_priv, unicast_packet->orig);
 188         if (!orig_node)
 189                 goto out;
 190
 191         orig_node->last_frag_packet = jiffies;
 192
 193         if (list_empty(&orig_node->frag_list) &&
 194             frag_create_buffer(&orig_node->frag_list)) {
 195                 pr_debug("couldn't create frag buffer\n");
 196                 goto out;
 197         }
 198
 199         tmp_frag_entry = frag_search_packet(&orig_node->frag_list,
 200                                             unicast_packet);
 201
 202         if (!tmp_frag_entry) {
 203                 frag_create_entry(&orig_node->frag_list, skb);
 204                 ret = NET_RX_SUCCESS;
 205                 goto out;
 206         }
 207
 208         *new_skb = frag_merge_packet(&orig_node->frag_list, tmp_frag_entry,
 209                                      skb);
 210         /* if not, merge failed */
 211         if (*new_skb)
 212                 ret = NET_RX_SUCCESS;
 213
 214 out:
 215         if (orig_node)
 216                 orig_node_free_ref(orig_node);
 217         return ret;
 218 }
 219
 220 int frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
 221                   struct hard_iface *hard_iface, uint8_t dstaddr[])
 222 {
 223         struct unicast_packet tmp_uc, *unicast_packet;
 224         struct sk_buff *frag_skb;
 225         struct unicast_frag_packet *frag1, *frag2;
 226         int uc_hdr_len = sizeof(struct unicast_packet);
 227         int ucf_hdr_len = sizeof(struct unicast_frag_packet);
 228         int data_len = skb->len - uc_hdr_len;
 229         int large_tail = 0;
 230         uint16_t seqno;
 231
 232         if (!bat_priv->primary_if)
 233                 goto dropped;
 234
 235         frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
 236         if (!frag_skb)
 237                 goto dropped;
 238         skb_reserve(frag_skb, ucf_hdr_len);
 239
 240         unicast_packet = (struct unicast_packet *) skb->data;
 241         memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
 242         skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
 243
 244         if (my_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
 245             my_skb_head_push(frag_skb, ucf_hdr_len) < 0)
 246                 goto drop_frag;
 247
 248         frag1 = (struct unicast_frag_packet *)skb->data;
 249         frag2 = (struct unicast_frag_packet *)frag_skb->data;
 250
 251         memcpy(frag1, &tmp_uc, sizeof(struct unicast_packet));
 252
 253         frag1->ttl--;
 254         frag1->version = COMPAT_VERSION;
 255         frag1->packet_type = BAT_UNICAST_FRAG;
 256
 257         memcpy(frag1->orig, bat_priv->primary_if->net_dev->dev_addr, ETH_ALEN);
 258         memcpy(frag2, frag1, sizeof(struct unicast_frag_packet));
 259
 260         if (data_len & 1)
 261                 large_tail = UNI_FRAG_LARGETAIL;
 262
 263         frag1->flags = UNI_FRAG_HEAD | large_tail;
 264         frag2->flags = large_tail;
 265
 266         seqno = atomic_add_return(2, &hard_iface->frag_seqno);
 267         frag1->seqno = htons(seqno - 1);
 268         frag2->seqno = htons(seqno);
 269
 270         send_skb_packet(skb, hard_iface, dstaddr);
 271         send_skb_packet(frag_skb, hard_iface, dstaddr);
 272         return NET_RX_SUCCESS;
 273
 274 drop_frag:
 275         kfree_skb(frag_skb);
 276 dropped:
 277         kfree_skb(skb);
 278         return NET_RX_DROP;
 279 }
 280
 281 int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
 282 {
 283         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 284         struct unicast_packet *unicast_packet;
 285         struct orig_node *orig_node;
 286         struct neigh_node *neigh_node;
 287         int data_len = skb->len;
 288         int ret = 1;
 289
 290         /* get routing information */
 291         if (is_multicast_ether_addr(ethhdr->h_dest)) {
 292                 orig_node = (struct orig_node *)gw_get_selected(bat_priv);
 293                 if (orig_node)
 294                         goto find_router;
 295         }
 296
 297         /* check for hna host - increases orig_node refcount */
 298         orig_node = transtable_search(bat_priv, ethhdr->h_dest);
 299
 300 find_router:
 301         /**
 302          * find_router():
 303          *  - if orig_node is NULL it returns NULL
 304          *  - increases neigh_nodes refcount if found.
 305          */
 306         neigh_node = find_router(bat_priv, orig_node, NULL);
 307
 308         if (!neigh_node)
 309                 goto out;
 310
 311         if (neigh_node->if_incoming->if_status != IF_ACTIVE)
 312                 goto out;
 313
 314         if (my_skb_head_push(skb, sizeof(struct unicast_packet)) < 0)
 315                 goto out;
 316
 317         unicast_packet = (struct unicast_packet *)skb->data;
 318
 319         unicast_packet->version = COMPAT_VERSION;
 320         /* batman packet type: unicast */
 321         unicast_packet->packet_type = BAT_UNICAST;
 322         /* set unicast ttl */
 323         unicast_packet->ttl = TTL;
 324         /* copy the destination for faster routing */
 325         memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
 326
 327         if (atomic_read(&bat_priv->fragmentation) &&
 328             data_len + sizeof(struct unicast_packet) >
 329                                 neigh_node->if_incoming->net_dev->mtu) {
 330                 /* send frag skb decreases ttl */
 331                 unicast_packet->ttl++;
 332                 ret = frag_send_skb(skb, bat_priv,
 333                                     neigh_node->if_incoming, neigh_node->addr);
 334                 goto out;
 335         }
 336
 337         send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
 338         ret = 0;
 339         goto out;
 340
 341 out:
 342         if (neigh_node)
 343                 neigh_node_free_ref(neigh_node);
 344         if (orig_node)
 345                 orig_node_free_ref(orig_node);
 346         if (ret == 1)
 347                 kfree_skb(skb);
 348         return ret;
 349 }