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(*unicast_packet);
  43         int uni_diff = sizeof(*up) - 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(*up));
  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(*tfp), GFP_ATOMIC);
 103                 if (!tfp) {
 104                         frag_list_free(head);
 105                         return -ENOMEM;
 106                 }
 107                 tfp->skb = NULL;
 108                 tfp->seqno = 0;
 109                 INIT_LIST_HEAD(&tfp->list);
 110                 list_add(&tfp->list, head);
 111         }
 112
 113         return 0;
 114 }
 115
 116 static struct frag_packet_list_entry *frag_search_packet(struct list_head *head,
 117                                            const struct unicast_frag_packet *up)
 118 {
 119         struct frag_packet_list_entry *tfp;
 120         struct unicast_frag_packet *tmp_up = NULL;
 121         uint16_t search_seqno;
 122
 123         if (up->flags & UNI_FRAG_HEAD)
 124                 search_seqno = ntohs(up->seqno)+1;
 125         else
 126                 search_seqno = ntohs(up->seqno)-1;
 127
 128         list_for_each_entry(tfp, head, list) {
 129
 130                 if (!tfp->skb)
 131                         continue;
 132
 133                 if (tfp->seqno == ntohs(up->seqno))
 134                         goto mov_tail;
 135
 136                 tmp_up = (struct unicast_frag_packet *)tfp->skb->data;
 137
 138                 if (tfp->seqno == search_seqno) {
 139
 140                         if ((tmp_up->flags & UNI_FRAG_HEAD) !=
 141                             (up->flags & UNI_FRAG_HEAD))
 142                                 return tfp;
 143                         else
 144                                 goto mov_tail;
 145                 }
 146         }
 147         return NULL;
 148
 149 mov_tail:
 150         list_move_tail(&tfp->list, head);
 151         return NULL;
 152 }
 153
 154 void frag_list_free(struct list_head *head)
 155 {
 156         struct frag_packet_list_entry *pf, *tmp_pf;
 157
 158         if (!list_empty(head)) {
 159
 160                 list_for_each_entry_safe(pf, tmp_pf, head, list) {
 161                         kfree_skb(pf->skb);
 162                         list_del(&pf->list);
 163                         kfree(pf);
 164                 }
 165         }
 166         return;
 167 }
 168
 169 /* frag_reassemble_skb():
 170  * returns NET_RX_DROP if the operation failed - skb is left intact
 171  * returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
 172  * or the skb could be reassembled (skb_new will point to the new packet and
 173  * skb was freed)
 174  */
 175 int frag_reassemble_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
 176                         struct sk_buff **new_skb)
 177 {
 178         struct orig_node *orig_node;
 179         struct frag_packet_list_entry *tmp_frag_entry;
 180         int ret = NET_RX_DROP;
 181         struct unicast_frag_packet *unicast_packet =
 182                 (struct unicast_frag_packet *)skb->data;
 183
 184         *new_skb = NULL;
 185
 186         orig_node = orig_hash_find(bat_priv, unicast_packet->orig);
 187         if (!orig_node)
 188                 goto out;
 189
 190         orig_node->last_frag_packet = jiffies;
 191
 192         if (list_empty(&orig_node->frag_list) &&
 193             frag_create_buffer(&orig_node->frag_list)) {
 194                 pr_debug("couldn't create frag buffer\n");
 195                 goto out;
 196         }
 197
 198         tmp_frag_entry = frag_search_packet(&orig_node->frag_list,
 199                                             unicast_packet);
 200
 201         if (!tmp_frag_entry) {
 202                 frag_create_entry(&orig_node->frag_list, skb);
 203                 ret = NET_RX_SUCCESS;
 204                 goto out;
 205         }
 206
 207         *new_skb = frag_merge_packet(&orig_node->frag_list, tmp_frag_entry,
 208                                      skb);
 209         /* if not, merge failed */
 210         if (*new_skb)
 211                 ret = NET_RX_SUCCESS;
 212
 213 out:
 214         if (orig_node)
 215                 orig_node_free_ref(orig_node);
 216         return ret;
 217 }
 218
 219 int frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
 220                   struct hard_iface *hard_iface, const uint8_t dstaddr[])
 221 {
 222         struct unicast_packet tmp_uc, *unicast_packet;
 223         struct hard_iface *primary_if;
 224         struct sk_buff *frag_skb;
 225         struct unicast_frag_packet *frag1, *frag2;
 226         int uc_hdr_len = sizeof(*unicast_packet);
 227         int ucf_hdr_len = sizeof(*frag1);
 228         int data_len = skb->len - uc_hdr_len;
 229         int large_tail = 0, ret = NET_RX_DROP;
 230         uint16_t seqno;
 231
 232         primary_if = primary_if_get_selected(bat_priv);
 233         if (!primary_if)
 234                 goto dropped;
 235
 236         frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
 237         if (!frag_skb)
 238                 goto dropped;
 239         skb_reserve(frag_skb, ucf_hdr_len);
 240
 241         unicast_packet = (struct unicast_packet *) skb->data;
 242         memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
 243         skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
 244
 245         if (my_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
 246             my_skb_head_push(frag_skb, ucf_hdr_len) < 0)
 247                 goto drop_frag;
 248
 249         frag1 = (struct unicast_frag_packet *)skb->data;
 250         frag2 = (struct unicast_frag_packet *)frag_skb->data;
 251
 252         memcpy(frag1, &tmp_uc, sizeof(tmp_uc));
 253
 254         frag1->ttl--;
 255         frag1->version = COMPAT_VERSION;
 256         frag1->packet_type = BAT_UNICAST_FRAG;
 257
 258         memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 259         memcpy(frag2, frag1, sizeof(*frag2));
 260
 261         if (data_len & 1)
 262                 large_tail = UNI_FRAG_LARGETAIL;
 263
 264         frag1->flags = UNI_FRAG_HEAD | large_tail;
 265         frag2->flags = large_tail;
 266
 267         seqno = atomic_add_return(2, &hard_iface->frag_seqno);
 268         frag1->seqno = htons(seqno - 1);
 269         frag2->seqno = htons(seqno);
 270
 271         send_skb_packet(skb, hard_iface, dstaddr);
 272         send_skb_packet(frag_skb, hard_iface, dstaddr);
 273         ret = NET_RX_SUCCESS;
 274         goto out;
 275
 276 drop_frag:
 277         kfree_skb(frag_skb);
 278 dropped:
 279         kfree_skb(skb);
 280 out:
 281         if (primary_if)
 282                 hardif_free_ref(primary_if);
 283         return ret;
 284 }
 285
 286 int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
 287 {
 288         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 289         struct unicast_packet *unicast_packet;
 290         struct orig_node *orig_node;
 291         struct neigh_node *neigh_node;
 292         int data_len = skb->len;
 293         int ret = 1;
 294
 295         /* get routing information */
 296         if (is_multicast_ether_addr(ethhdr->h_dest)) {
 297                 orig_node = gw_get_selected_orig(bat_priv);
 298                 if (orig_node)
 299                         goto find_router;
 300         }
 301
 302         /* check for tt host - increases orig_node refcount */
 303         orig_node = transtable_search(bat_priv, ethhdr->h_dest);
 304
 305 find_router:
 306         /**
 307          * find_router():
 308          *  - if orig_node is NULL it returns NULL
 309          *  - increases neigh_nodes refcount if found.
 310          */
 311         neigh_node = find_router(bat_priv, orig_node, NULL);
 312
 313         if (!neigh_node)
 314                 goto out;
 315
 316         if (my_skb_head_push(skb, sizeof(*unicast_packet)) < 0)
 317                 goto out;
 318
 319         unicast_packet = (struct unicast_packet *)skb->data;
 320
 321         unicast_packet->version = COMPAT_VERSION;
 322         /* batman packet type: unicast */
 323         unicast_packet->packet_type = BAT_UNICAST;
 324         /* set unicast ttl */
 325         unicast_packet->ttl = TTL;
 326         /* copy the destination for faster routing */
 327         memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
 328         /* set the destination tt version number */
 329         unicast_packet->ttvn =
 330                 (uint8_t)atomic_read(&orig_node->last_ttvn);
 331
 332         if (atomic_read(&bat_priv->fragmentation) &&
 333             data_len + sizeof(*unicast_packet) >
 334                                 neigh_node->if_incoming->net_dev->mtu) {
 335                 /* send frag skb decreases ttl */
 336                 unicast_packet->ttl++;
 337                 ret = frag_send_skb(skb, bat_priv,
 338                                     neigh_node->if_incoming, neigh_node->addr);
 339                 goto out;
 340         }
 341
 342         send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
 343         ret = 0;
 344         goto out;
 345
 346 out:
 347         if (neigh_node)
 348                 neigh_node_free_ref(neigh_node);
 349         if (orig_node)
 350                 orig_node_free_ref(orig_node);
 351         if (ret == 1)
 352                 kfree_skb(skb);
 353         return ret;
 354 }