unicast.c revision 96412690116afcc1b2705615b5a7c8dc6c5e905f 
1/* Copyright (C) 2010-2012 B.A.T.M.A.N. contributors:
2 *
3 * Andreas Langer
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of version 2 of the GNU General Public
7 * License as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 * 02110-1301, USA
18 */
19
20#include "main.h"
21#include "unicast.h"
22#include "send.h"
23#include "soft-interface.h"
24#include "gateway_client.h"
25#include "originator.h"
26#include "hash.h"
27#include "translation-table.h"
28#include "routing.h"
29#include "hard-interface.h"
30
31
32static struct sk_buff *
33batadv_frag_merge_packet(struct list_head *head,
34			 struct frag_packet_list_entry *tfp,
35			 struct sk_buff *skb)
36{
37	struct batadv_unicast_frag_packet *up;
38	struct sk_buff *tmp_skb;
39	struct batadv_unicast_packet *unicast_packet;
40	int hdr_len = sizeof(*unicast_packet);
41	int uni_diff = sizeof(*up) - hdr_len;
42
43	up = (struct batadv_unicast_frag_packet *)skb->data;
44	/* set skb to the first part and tmp_skb to the second part */
45	if (up->flags & BATADV_UNI_FRAG_HEAD) {
46		tmp_skb = tfp->skb;
47	} else {
48		tmp_skb = skb;
49		skb = tfp->skb;
50	}
51
52	if (skb_linearize(skb) < 0 || skb_linearize(tmp_skb) < 0)
53		goto err;
54
55	skb_pull(tmp_skb, sizeof(*up));
56	if (pskb_expand_head(skb, 0, tmp_skb->len, GFP_ATOMIC) < 0)
57		goto err;
58
59	/* move free entry to end */
60	tfp->skb = NULL;
61	tfp->seqno = 0;
62	list_move_tail(&tfp->list, head);
63
64	memcpy(skb_put(skb, tmp_skb->len), tmp_skb->data, tmp_skb->len);
65	kfree_skb(tmp_skb);
66
67	memmove(skb->data + uni_diff, skb->data, hdr_len);
68	unicast_packet = (struct batadv_unicast_packet *)skb_pull(skb,
69								  uni_diff);
70	unicast_packet->header.packet_type = BATADV_UNICAST;
71
72	return skb;
73
74err:
75	/* free buffered skb, skb will be freed later */
76	kfree_skb(tfp->skb);
77	return NULL;
78}
79
80static void batadv_frag_create_entry(struct list_head *head,
81				     struct sk_buff *skb)
82{
83	struct frag_packet_list_entry *tfp;
84	struct batadv_unicast_frag_packet *up;
85
86	up = (struct batadv_unicast_frag_packet *)skb->data;
87
88	/* free and oldest packets stand at the end */
89	tfp = list_entry((head)->prev, typeof(*tfp), list);
90	kfree_skb(tfp->skb);
91
92	tfp->seqno = ntohs(up->seqno);
93	tfp->skb = skb;
94	list_move(&tfp->list, head);
95	return;
96}
97
98static int batadv_frag_create_buffer(struct list_head *head)
99{
100	int i;
101	struct frag_packet_list_entry *tfp;
102
103	for (i = 0; i < BATADV_FRAG_BUFFER_SIZE; i++) {
104		tfp = kmalloc(sizeof(*tfp), GFP_ATOMIC);
105		if (!tfp) {
106			batadv_frag_list_free(head);
107			return -ENOMEM;
108		}
109		tfp->skb = NULL;
110		tfp->seqno = 0;
111		INIT_LIST_HEAD(&tfp->list);
112		list_add(&tfp->list, head);
113	}
114
115	return 0;
116}
117
118static struct frag_packet_list_entry *
119batadv_frag_search_packet(struct list_head *head,
120			  const struct batadv_unicast_frag_packet *up)
121{
122	struct frag_packet_list_entry *tfp;
123	struct batadv_unicast_frag_packet *tmp_up = NULL;
124	uint16_t search_seqno;
125
126	if (up->flags & BATADV_UNI_FRAG_HEAD)
127		search_seqno = ntohs(up->seqno)+1;
128	else
129		search_seqno = ntohs(up->seqno)-1;
130
131	list_for_each_entry(tfp, head, list) {
132
133		if (!tfp->skb)
134			continue;
135
136		if (tfp->seqno == ntohs(up->seqno))
137			goto mov_tail;
138
139		tmp_up = (struct batadv_unicast_frag_packet *)tfp->skb->data;
140
141		if (tfp->seqno == search_seqno) {
142
143			if ((tmp_up->flags & BATADV_UNI_FRAG_HEAD) !=
144			    (up->flags & BATADV_UNI_FRAG_HEAD))
145				return tfp;
146			else
147				goto mov_tail;
148		}
149	}
150	return NULL;
151
152mov_tail:
153	list_move_tail(&tfp->list, head);
154	return NULL;
155}
156
157void batadv_frag_list_free(struct list_head *head)
158{
159	struct frag_packet_list_entry *pf, *tmp_pf;
160
161	if (!list_empty(head)) {
162
163		list_for_each_entry_safe(pf, tmp_pf, head, list) {
164			kfree_skb(pf->skb);
165			list_del(&pf->list);
166			kfree(pf);
167		}
168	}
169	return;
170}
171
172/* frag_reassemble_skb():
173 * returns NET_RX_DROP if the operation failed - skb is left intact
174 * returns NET_RX_SUCCESS if the fragment was buffered (skb_new will be NULL)
175 * or the skb could be reassembled (skb_new will point to the new packet and
176 * skb was freed)
177 */
178int batadv_frag_reassemble_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
179			       struct sk_buff **new_skb)
180{
181	struct orig_node *orig_node;
182	struct frag_packet_list_entry *tmp_frag_entry;
183	int ret = NET_RX_DROP;
184	struct batadv_unicast_frag_packet *unicast_packet;
185
186	unicast_packet = (struct batadv_unicast_frag_packet *)skb->data;
187	*new_skb = NULL;
188
189	orig_node = batadv_orig_hash_find(bat_priv, unicast_packet->orig);
190	if (!orig_node)
191		goto out;
192
193	orig_node->last_frag_packet = jiffies;
194
195	if (list_empty(&orig_node->frag_list) &&
196	    batadv_frag_create_buffer(&orig_node->frag_list)) {
197		pr_debug("couldn't create frag buffer\n");
198		goto out;
199	}
200
201	tmp_frag_entry = batadv_frag_search_packet(&orig_node->frag_list,
202						   unicast_packet);
203
204	if (!tmp_frag_entry) {
205		batadv_frag_create_entry(&orig_node->frag_list, skb);
206		ret = NET_RX_SUCCESS;
207		goto out;
208	}
209
210	*new_skb = batadv_frag_merge_packet(&orig_node->frag_list,
211					    tmp_frag_entry, skb);
212	/* if not, merge failed */
213	if (*new_skb)
214		ret = NET_RX_SUCCESS;
215
216out:
217	if (orig_node)
218		batadv_orig_node_free_ref(orig_node);
219	return ret;
220}
221
222int batadv_frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
223			 struct hard_iface *hard_iface, const uint8_t dstaddr[])
224{
225	struct batadv_unicast_packet tmp_uc, *unicast_packet;
226	struct hard_iface *primary_if;
227	struct sk_buff *frag_skb;
228	struct batadv_unicast_frag_packet *frag1, *frag2;
229	int uc_hdr_len = sizeof(*unicast_packet);
230	int ucf_hdr_len = sizeof(*frag1);
231	int data_len = skb->len - uc_hdr_len;
232	int large_tail = 0, ret = NET_RX_DROP;
233	uint16_t seqno;
234
235	primary_if = batadv_primary_if_get_selected(bat_priv);
236	if (!primary_if)
237		goto dropped;
238
239	frag_skb = dev_alloc_skb(data_len - (data_len / 2) + ucf_hdr_len);
240	if (!frag_skb)
241		goto dropped;
242	skb_reserve(frag_skb, ucf_hdr_len);
243
244	unicast_packet = (struct batadv_unicast_packet *)skb->data;
245	memcpy(&tmp_uc, unicast_packet, uc_hdr_len);
246	skb_split(skb, frag_skb, data_len / 2 + uc_hdr_len);
247
248	if (batadv_skb_head_push(skb, ucf_hdr_len - uc_hdr_len) < 0 ||
249	    batadv_skb_head_push(frag_skb, ucf_hdr_len) < 0)
250		goto drop_frag;
251
252	frag1 = (struct batadv_unicast_frag_packet *)skb->data;
253	frag2 = (struct batadv_unicast_frag_packet *)frag_skb->data;
254
255	memcpy(frag1, &tmp_uc, sizeof(tmp_uc));
256
257	frag1->header.ttl--;
258	frag1->header.version = BATADV_COMPAT_VERSION;
259	frag1->header.packet_type = BATADV_UNICAST_FRAG;
260
261	memcpy(frag1->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
262	memcpy(frag2, frag1, sizeof(*frag2));
263
264	if (data_len & 1)
265		large_tail = BATADV_UNI_FRAG_LARGETAIL;
266
267	frag1->flags = BATADV_UNI_FRAG_HEAD | large_tail;
268	frag2->flags = large_tail;
269
270	seqno = atomic_add_return(2, &hard_iface->frag_seqno);
271	frag1->seqno = htons(seqno - 1);
272	frag2->seqno = htons(seqno);
273
274	batadv_send_skb_packet(skb, hard_iface, dstaddr);
275	batadv_send_skb_packet(frag_skb, hard_iface, dstaddr);
276	ret = NET_RX_SUCCESS;
277	goto out;
278
279drop_frag:
280	kfree_skb(frag_skb);
281dropped:
282	kfree_skb(skb);
283out:
284	if (primary_if)
285		batadv_hardif_free_ref(primary_if);
286	return ret;
287}
288
289int batadv_unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv)
290{
291	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
292	struct batadv_unicast_packet *unicast_packet;
293	struct orig_node *orig_node;
294	struct neigh_node *neigh_node;
295	int data_len = skb->len;
296	int ret = 1;
297
298	/* get routing information */
299	if (is_multicast_ether_addr(ethhdr->h_dest)) {
300		orig_node = batadv_gw_get_selected_orig(bat_priv);
301		if (orig_node)
302			goto find_router;
303	}
304
305	/* check for tt host - increases orig_node refcount.
306	 * returns NULL in case of AP isolation
307	 */
308	orig_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
309					     ethhdr->h_dest);
310find_router:
311	/* find_router():
312	 *  - if orig_node is NULL it returns NULL
313	 *  - increases neigh_nodes refcount if found.
314	 */
315	neigh_node = batadv_find_router(bat_priv, orig_node, NULL);
316	if (!neigh_node)
317		goto out;
318
319	if (batadv_skb_head_push(skb, sizeof(*unicast_packet)) < 0)
320		goto out;
321
322	unicast_packet = (struct batadv_unicast_packet *)skb->data;
323
324	unicast_packet->header.version = BATADV_COMPAT_VERSION;
325	/* batman packet type: unicast */
326	unicast_packet->header.packet_type = BATADV_UNICAST;
327	/* set unicast ttl */
328	unicast_packet->header.ttl = BATADV_TTL;
329	/* copy the destination for faster routing */
330	memcpy(unicast_packet->dest, orig_node->orig, ETH_ALEN);
331	/* set the destination tt version number */
332	unicast_packet->ttvn =
333		(uint8_t)atomic_read(&orig_node->last_ttvn);
334
335	/* inform the destination node that we are still missing a correct route
336	 * for this client. The destination will receive this packet and will
337	 * try to reroute it because the ttvn contained in the header is less
338	 * than the current one
339	 */
340	if (batadv_tt_global_client_is_roaming(bat_priv, ethhdr->h_dest))
341		unicast_packet->ttvn = unicast_packet->ttvn - 1;
342
343	if (atomic_read(&bat_priv->fragmentation) &&
344	    data_len + sizeof(*unicast_packet) >
345				neigh_node->if_incoming->net_dev->mtu) {
346		/* send frag skb decreases ttl */
347		unicast_packet->header.ttl++;
348		ret = batadv_frag_send_skb(skb, bat_priv,
349					   neigh_node->if_incoming,
350					   neigh_node->addr);
351		goto out;
352	}
353
354	batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
355	ret = 0;
356	goto out;
357
358out:
359	if (neigh_node)
360		batadv_neigh_node_free_ref(neigh_node);
361	if (orig_node)
362		batadv_orig_node_free_ref(orig_node);
363	if (ret == 1)
364		kfree_skb(skb);
365	return ret;
366}
367