unicast.c revision 2dafb49d84a9195193b28ac5047df1bbab6053b9 
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
34static 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
74err:
75	/* free buffered skb, skb will be freed later */
76	kfree_skb(tfp->skb);
77	return NULL;
78}
79
80static 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
96static 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
117static 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
150mov_tail:
151	list_move_tail(&tfp->list, head);
152	return NULL;
153}
154
155void 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 */
176int 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
214out:
215	if (orig_node)
216		orig_node_free_ref(orig_node);
217	return ret;
218}
219
220int 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
277drop_frag:
278	kfree_skb(frag_skb);
279dropped:
280	kfree_skb(skb);
281out:
282	if (primary_if)
283		hardif_free_ref(primary_if);
284	return ret;
285}
286
287int 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
306find_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
347out:
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