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TOMOYO Linux Cross Reference
Linux/net/batman-adv/unicast.c

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  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 hard_iface *primary_if;
225         struct sk_buff *frag_skb;
226         struct unicast_frag_packet *frag1, *frag2;
227         int uc_hdr_len = sizeof(struct unicast_packet);
228         int ucf_hdr_len = sizeof(struct unicast_frag_packet);
229         int data_len = skb->len - uc_hdr_len;
230         int large_tail = 0, ret = NET_RX_DROP;
231         uint16_t seqno;
232 
233         primary_if = primary_if_get_selected(bat_priv);
234         if (!primary_if)
235                 goto dropped;
236 
237         frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
238         if (!frag_skb)
239                 goto dropped;
240         skb_reserve(frag_skb, ucf_hdr_len);
241 
242         unicast_packet = (struct unicast_packet *) skb->data;
243         memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
244         skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
245 
246         if (my_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
247             my_skb_head_push(frag_skb, ucf_hdr_len) < 0)
248                 goto drop_frag;
249 
250         frag1 = (struct unicast_frag_packet *)skb->data;
251         frag2 = (struct unicast_frag_packet *)frag_skb->data;
252 
253         memcpy(frag1, &tmp_uc, sizeof(struct unicast_packet));
254 
255         frag1->ttl--;
256         frag1->version = COMPAT_VERSION;
257         frag1->packet_type = BAT_UNICAST_FRAG;
258 
259         memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
260         memcpy(frag2, frag1, sizeof(struct unicast_frag_packet));
261 
262         if (data_len & 1)
263                 large_tail = UNI_FRAG_LARGETAIL;
264 
265         frag1->flags = UNI_FRAG_HEAD | large_tail;
266         frag2->flags = large_tail;
267 
268         seqno = atomic_add_return(2, &hard_iface->frag_seqno);
269         frag1->seqno = htons(seqno - 1);
270         frag2->seqno = htons(seqno);
271 
272         send_skb_packet(skb, hard_iface, dstaddr);
273         send_skb_packet(frag_skb, hard_iface, dstaddr);
274         ret = NET_RX_SUCCESS;
275         goto out;
276 
277 drop_frag:
278         kfree_skb(frag_skb);
279 dropped:
280         kfree_skb(skb);
281 out:
282         if (primary_if)
283                 hardif_free_ref(primary_if);
284         return ret;
285 }
286 
287 int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
288 {
289         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
290         struct unicast_packet *unicast_packet;
291         struct orig_node *orig_node;
292         struct neigh_node *neigh_node;
293         int data_len = skb->len;
294         int ret = 1;
295 
296         /* get routing information */
297         if (is_multicast_ether_addr(ethhdr->h_dest)) {
298                 orig_node = (struct orig_node *)gw_get_selected_orig(bat_priv);
299                 if (orig_node)
300                         goto find_router;
301         }
302 
303         /* check for tt host - increases orig_node refcount */
304         orig_node = transtable_search(bat_priv, ethhdr->h_dest);
305 
306 find_router:
307         /**
308          * find_router():
309          *  - if orig_node is NULL it returns NULL
310          *  - increases neigh_nodes refcount if found.
311          */
312         neigh_node = find_router(bat_priv, orig_node, NULL);
313 
314         if (!neigh_node)
315                 goto out;
316 
317         if (neigh_node->if_incoming->if_status != IF_ACTIVE)
318                 goto out;
319 
320         if (my_skb_head_push(skb, sizeof(struct unicast_packet)) < 0)
321                 goto out;
322 
323         unicast_packet = (struct unicast_packet *)skb->data;
324 
325         unicast_packet->version = COMPAT_VERSION;
326         /* batman packet type: unicast */
327         unicast_packet->packet_type = BAT_UNICAST;
328         /* set unicast ttl */
329         unicast_packet->ttl = TTL;
330         /* copy the destination for faster routing */
331         memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
332 
333         if (atomic_read(&bat_priv->fragmentation) &&
334             data_len + sizeof(struct unicast_packet) >
335                                 neigh_node->if_incoming->net_dev->mtu) {
336                 /* send frag skb decreases ttl */
337                 unicast_packet->ttl++;
338                 ret = frag_send_skb(skb, bat_priv,
339                                     neigh_node->if_incoming, neigh_node->addr);
340                 goto out;
341         }
342 
343         send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
344         ret = 0;
345         goto out;
346 
347 out:
348         if (neigh_node)
349                 neigh_node_free_ref(neigh_node);
350         if (orig_node)
351                 orig_node_free_ref(orig_node);
352         if (ret == 1)
353                 kfree_skb(skb);
354         return ret;
355 }
356 

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