1/* This program is free software; you can redistribute it and/or modify
2 * it under the terms of the GNU General Public License version 2
3 * as published by the Free Software Foundation.
4 *
5 * This program is distributed in the hope that it will be useful,
6 * but WITHOUT ANY WARRANTY; without even the implied warranty of
7 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
8 * GNU General Public License for more details.
9 */
10
11#include <net/6lowpan.h>
12#include <net/ieee802154_netdev.h>
13#include <net/mac802154.h>
14
15#include "6lowpan_i.h"
16
17#define LOWPAN_FRAG1_HEAD_SIZE	0x4
18#define LOWPAN_FRAGN_HEAD_SIZE	0x5
19
20/* don't save pan id, it's intra pan */
21struct lowpan_addr {
22	u8 mode;
23	union {
24		/* IPv6 needs big endian here */
25		__be64 extended_addr;
26		__be16 short_addr;
27	} u;
28};
29
30struct lowpan_addr_info {
31	struct lowpan_addr daddr;
32	struct lowpan_addr saddr;
33};
34
35static inline struct
36lowpan_addr_info *lowpan_skb_priv(const struct sk_buff *skb)
37{
38	WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct lowpan_addr_info));
39	return (struct lowpan_addr_info *)(skb->data -
40			sizeof(struct lowpan_addr_info));
41}
42
43/* This callback will be called from AF_PACKET and IPv6 stack, the AF_PACKET
44 * sockets gives an 8 byte array for addresses only!
45 *
46 * TODO I think AF_PACKET DGRAM (sending/receiving) RAW (sending) makes no
47 * sense here. We should disable it, the right use-case would be AF_INET6
48 * RAW/DGRAM sockets.
49 */
50int lowpan_header_create(struct sk_buff *skb, struct net_device *ldev,
51			 unsigned short type, const void *_daddr,
52			 const void *_saddr, unsigned int len)
53{
54	const u8 *saddr = _saddr;
55	const u8 *daddr = _daddr;
56	struct lowpan_addr_info *info;
57
58	/* TODO:
59	 * if this package isn't ipv6 one, where should it be routed?
60	 */
61	if (type != ETH_P_IPV6)
62		return 0;
63
64	if (!saddr)
65		saddr = ldev->dev_addr;
66
67	raw_dump_inline(__func__, "saddr", (unsigned char *)saddr, 8);
68	raw_dump_inline(__func__, "daddr", (unsigned char *)daddr, 8);
69
70	info = lowpan_skb_priv(skb);
71
72	/* TODO: Currently we only support extended_addr */
73	info->daddr.mode = IEEE802154_ADDR_LONG;
74	memcpy(&info->daddr.u.extended_addr, daddr,
75	       sizeof(info->daddr.u.extended_addr));
76	info->saddr.mode = IEEE802154_ADDR_LONG;
77	memcpy(&info->saddr.u.extended_addr, saddr,
78	       sizeof(info->daddr.u.extended_addr));
79
80	return 0;
81}
82
83static struct sk_buff*
84lowpan_alloc_frag(struct sk_buff *skb, int size,
85		  const struct ieee802154_hdr *master_hdr, bool frag1)
86{
87	struct net_device *wdev = lowpan_dev_info(skb->dev)->wdev;
88	struct sk_buff *frag;
89	int rc;
90
91	frag = alloc_skb(wdev->needed_headroom + wdev->needed_tailroom + size,
92			 GFP_ATOMIC);
93
94	if (likely(frag)) {
95		frag->dev = wdev;
96		frag->priority = skb->priority;
97		skb_reserve(frag, wdev->needed_headroom);
98		skb_reset_network_header(frag);
99		*mac_cb(frag) = *mac_cb(skb);
100
101		if (frag1) {
102			memcpy(skb_put(frag, skb->mac_len),
103			       skb_mac_header(skb), skb->mac_len);
104		} else {
105			rc = wpan_dev_hard_header(frag, wdev,
106						  &master_hdr->dest,
107						  &master_hdr->source, size);
108			if (rc < 0) {
109				kfree_skb(frag);
110				return ERR_PTR(rc);
111			}
112		}
113	} else {
114		frag = ERR_PTR(-ENOMEM);
115	}
116
117	return frag;
118}
119
120static int
121lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
122		     u8 *frag_hdr, int frag_hdrlen,
123		     int offset, int len, bool frag1)
124{
125	struct sk_buff *frag;
126
127	raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
128
129	frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr, frag1);
130	if (IS_ERR(frag))
131		return PTR_ERR(frag);
132
133	memcpy(skb_put(frag, frag_hdrlen), frag_hdr, frag_hdrlen);
134	memcpy(skb_put(frag, len), skb_network_header(skb) + offset, len);
135
136	raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
137
138	return dev_queue_xmit(frag);
139}
140
141static int
142lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *ldev,
143		       const struct ieee802154_hdr *wpan_hdr, u16 dgram_size,
144		       u16 dgram_offset)
145{
146	__be16 frag_tag;
147	u8 frag_hdr[5];
148	int frag_cap, frag_len, payload_cap, rc;
149	int skb_unprocessed, skb_offset;
150
151	frag_tag = htons(lowpan_dev_info(ldev)->fragment_tag);
152	lowpan_dev_info(ldev)->fragment_tag++;
153
154	frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
155	frag_hdr[1] = dgram_size & 0xff;
156	memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
157
158	payload_cap = ieee802154_max_payload(wpan_hdr);
159
160	frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
161			      skb_network_header_len(skb), 8);
162
163	skb_offset = skb_network_header_len(skb);
164	skb_unprocessed = skb->len - skb->mac_len - skb_offset;
165
166	rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
167				  LOWPAN_FRAG1_HEAD_SIZE, 0,
168				  frag_len + skb_network_header_len(skb),
169				  true);
170	if (rc) {
171		pr_debug("%s unable to send FRAG1 packet (tag: %d)",
172			 __func__, ntohs(frag_tag));
173		goto err;
174	}
175
176	frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
177	frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
178	frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
179
180	do {
181		dgram_offset += frag_len;
182		skb_offset += frag_len;
183		skb_unprocessed -= frag_len;
184		frag_len = min(frag_cap, skb_unprocessed);
185
186		frag_hdr[4] = dgram_offset >> 3;
187
188		rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
189					  LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
190					  frag_len, false);
191		if (rc) {
192			pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
193				 __func__, ntohs(frag_tag), skb_offset);
194			goto err;
195		}
196	} while (skb_unprocessed > frag_cap);
197
198	ldev->stats.tx_packets++;
199	ldev->stats.tx_bytes += dgram_size;
200	consume_skb(skb);
201	return NET_XMIT_SUCCESS;
202
203err:
204	kfree_skb(skb);
205	return rc;
206}
207
208static int lowpan_header(struct sk_buff *skb, struct net_device *ldev,
209			 u16 *dgram_size, u16 *dgram_offset)
210{
211	struct wpan_dev *wpan_dev = lowpan_dev_info(ldev)->wdev->ieee802154_ptr;
212	struct ieee802154_addr sa, da;
213	struct ieee802154_mac_cb *cb = mac_cb_init(skb);
214	struct lowpan_addr_info info;
215	void *daddr, *saddr;
216
217	memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
218
219	/* TODO: Currently we only support extended_addr */
220	daddr = &info.daddr.u.extended_addr;
221	saddr = &info.saddr.u.extended_addr;
222
223	*dgram_size = skb->len;
224	lowpan_header_compress(skb, ldev, daddr, saddr);
225	/* dgram_offset = (saved bytes after compression) + lowpan header len */
226	*dgram_offset = (*dgram_size - skb->len) + skb_network_header_len(skb);
227
228	cb->type = IEEE802154_FC_TYPE_DATA;
229
230	/* prepare wpan address data */
231	sa.mode = IEEE802154_ADDR_LONG;
232	sa.pan_id = wpan_dev->pan_id;
233	sa.extended_addr = ieee802154_devaddr_from_raw(saddr);
234
235	/* intra-PAN communications */
236	da.pan_id = sa.pan_id;
237
238	/* if the destination address is the broadcast address, use the
239	 * corresponding short address
240	 */
241	if (!memcmp(daddr, ldev->broadcast, EUI64_ADDR_LEN)) {
242		da.mode = IEEE802154_ADDR_SHORT;
243		da.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
244		cb->ackreq = false;
245	} else {
246		da.mode = IEEE802154_ADDR_LONG;
247		da.extended_addr = ieee802154_devaddr_from_raw(daddr);
248		cb->ackreq = wpan_dev->ackreq;
249	}
250
251	return wpan_dev_hard_header(skb, lowpan_dev_info(ldev)->wdev, &da, &sa,
252				    0);
253}
254
255netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *ldev)
256{
257	struct ieee802154_hdr wpan_hdr;
258	int max_single, ret;
259	u16 dgram_size, dgram_offset;
260
261	pr_debug("package xmit\n");
262
263	WARN_ON_ONCE(skb->len > IPV6_MIN_MTU);
264
265	/* We must take a copy of the skb before we modify/replace the ipv6
266	 * header as the header could be used elsewhere
267	 */
268	skb = skb_unshare(skb, GFP_ATOMIC);
269	if (!skb)
270		return NET_XMIT_DROP;
271
272	ret = lowpan_header(skb, ldev, &dgram_size, &dgram_offset);
273	if (ret < 0) {
274		kfree_skb(skb);
275		return NET_XMIT_DROP;
276	}
277
278	if (ieee802154_hdr_peek(skb, &wpan_hdr) < 0) {
279		kfree_skb(skb);
280		return NET_XMIT_DROP;
281	}
282
283	max_single = ieee802154_max_payload(&wpan_hdr);
284
285	if (skb_tail_pointer(skb) - skb_network_header(skb) <= max_single) {
286		skb->dev = lowpan_dev_info(ldev)->wdev;
287		ldev->stats.tx_packets++;
288		ldev->stats.tx_bytes += dgram_size;
289		return dev_queue_xmit(skb);
290	} else {
291		netdev_tx_t rc;
292
293		pr_debug("frame is too big, fragmentation is needed\n");
294		rc = lowpan_xmit_fragmented(skb, ldev, &wpan_hdr, dgram_size,
295					    dgram_offset);
296
297		return rc < 0 ? NET_XMIT_DROP : rc;
298	}
299}
300