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
14#include "6lowpan_i.h"
15
16/* don't save pan id, it's intra pan */
17struct lowpan_addr {
18	u8 mode;
19	union {
20		/* IPv6 needs big endian here */
21		__be64 extended_addr;
22		__be16 short_addr;
23	} u;
24};
25
26struct lowpan_addr_info {
27	struct lowpan_addr daddr;
28	struct lowpan_addr saddr;
29};
30
31static inline struct
32lowpan_addr_info *lowpan_skb_priv(const struct sk_buff *skb)
33{
34	WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct lowpan_addr_info));
35	return (struct lowpan_addr_info *)(skb->data -
36			sizeof(struct lowpan_addr_info));
37}
38
39int lowpan_header_create(struct sk_buff *skb, struct net_device *dev,
40			 unsigned short type, const void *_daddr,
41			 const void *_saddr, unsigned int len)
42{
43	const u8 *saddr = _saddr;
44	const u8 *daddr = _daddr;
45	struct lowpan_addr_info *info;
46
47	/* TODO:
48	 * if this package isn't ipv6 one, where should it be routed?
49	 */
50	if (type != ETH_P_IPV6)
51		return 0;
52
53	if (!saddr)
54		saddr = dev->dev_addr;
55
56	raw_dump_inline(__func__, "saddr", (unsigned char *)saddr, 8);
57	raw_dump_inline(__func__, "daddr", (unsigned char *)daddr, 8);
58
59	info = lowpan_skb_priv(skb);
60
61	/* TODO: Currently we only support extended_addr */
62	info->daddr.mode = IEEE802154_ADDR_LONG;
63	memcpy(&info->daddr.u.extended_addr, daddr,
64	       sizeof(info->daddr.u.extended_addr));
65	info->saddr.mode = IEEE802154_ADDR_LONG;
66	memcpy(&info->saddr.u.extended_addr, saddr,
67	       sizeof(info->daddr.u.extended_addr));
68
69	return 0;
70}
71
72static struct sk_buff*
73lowpan_alloc_frag(struct sk_buff *skb, int size,
74		  const struct ieee802154_hdr *master_hdr)
75{
76	struct net_device *real_dev = lowpan_dev_info(skb->dev)->real_dev;
77	struct sk_buff *frag;
78	int rc;
79
80	frag = alloc_skb(real_dev->hard_header_len +
81			 real_dev->needed_tailroom + size,
82			 GFP_ATOMIC);
83
84	if (likely(frag)) {
85		frag->dev = real_dev;
86		frag->priority = skb->priority;
87		skb_reserve(frag, real_dev->hard_header_len);
88		skb_reset_network_header(frag);
89		*mac_cb(frag) = *mac_cb(skb);
90
91		rc = dev_hard_header(frag, real_dev, 0, &master_hdr->dest,
92				     &master_hdr->source, size);
93		if (rc < 0) {
94			kfree_skb(frag);
95			return ERR_PTR(rc);
96		}
97	} else {
98		frag = ERR_PTR(-ENOMEM);
99	}
100
101	return frag;
102}
103
104static int
105lowpan_xmit_fragment(struct sk_buff *skb, const struct ieee802154_hdr *wpan_hdr,
106		     u8 *frag_hdr, int frag_hdrlen,
107		     int offset, int len)
108{
109	struct sk_buff *frag;
110
111	raw_dump_inline(__func__, " fragment header", frag_hdr, frag_hdrlen);
112
113	frag = lowpan_alloc_frag(skb, frag_hdrlen + len, wpan_hdr);
114	if (IS_ERR(frag))
115		return -PTR_ERR(frag);
116
117	memcpy(skb_put(frag, frag_hdrlen), frag_hdr, frag_hdrlen);
118	memcpy(skb_put(frag, len), skb_network_header(skb) + offset, len);
119
120	raw_dump_table(__func__, " fragment dump", frag->data, frag->len);
121
122	return dev_queue_xmit(frag);
123}
124
125static int
126lowpan_xmit_fragmented(struct sk_buff *skb, struct net_device *dev,
127		       const struct ieee802154_hdr *wpan_hdr)
128{
129	u16 dgram_size, dgram_offset;
130	__be16 frag_tag;
131	u8 frag_hdr[5];
132	int frag_cap, frag_len, payload_cap, rc;
133	int skb_unprocessed, skb_offset;
134
135	dgram_size = lowpan_uncompress_size(skb, &dgram_offset) -
136		     skb->mac_len;
137	frag_tag = htons(lowpan_dev_info(dev)->fragment_tag);
138	lowpan_dev_info(dev)->fragment_tag++;
139
140	frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
141	frag_hdr[1] = dgram_size & 0xff;
142	memcpy(frag_hdr + 2, &frag_tag, sizeof(frag_tag));
143
144	payload_cap = ieee802154_max_payload(wpan_hdr);
145
146	frag_len = round_down(payload_cap - LOWPAN_FRAG1_HEAD_SIZE -
147			      skb_network_header_len(skb), 8);
148
149	skb_offset = skb_network_header_len(skb);
150	skb_unprocessed = skb->len - skb->mac_len - skb_offset;
151
152	rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
153				  LOWPAN_FRAG1_HEAD_SIZE, 0,
154				  frag_len + skb_network_header_len(skb));
155	if (rc) {
156		pr_debug("%s unable to send FRAG1 packet (tag: %d)",
157			 __func__, ntohs(frag_tag));
158		goto err;
159	}
160
161	frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;
162	frag_hdr[0] |= LOWPAN_DISPATCH_FRAGN;
163	frag_cap = round_down(payload_cap - LOWPAN_FRAGN_HEAD_SIZE, 8);
164
165	do {
166		dgram_offset += frag_len;
167		skb_offset += frag_len;
168		skb_unprocessed -= frag_len;
169		frag_len = min(frag_cap, skb_unprocessed);
170
171		frag_hdr[4] = dgram_offset >> 3;
172
173		rc = lowpan_xmit_fragment(skb, wpan_hdr, frag_hdr,
174					  LOWPAN_FRAGN_HEAD_SIZE, skb_offset,
175					  frag_len);
176		if (rc) {
177			pr_debug("%s unable to send a FRAGN packet. (tag: %d, offset: %d)\n",
178				 __func__, ntohs(frag_tag), skb_offset);
179			goto err;
180		}
181	} while (skb_unprocessed > frag_cap);
182
183	consume_skb(skb);
184	return NET_XMIT_SUCCESS;
185
186err:
187	kfree_skb(skb);
188	return rc;
189}
190
191static int lowpan_header(struct sk_buff *skb, struct net_device *dev)
192{
193	struct ieee802154_addr sa, da;
194	struct ieee802154_mac_cb *cb = mac_cb_init(skb);
195	struct lowpan_addr_info info;
196	void *daddr, *saddr;
197
198	memcpy(&info, lowpan_skb_priv(skb), sizeof(info));
199
200	/* TODO: Currently we only support extended_addr */
201	daddr = &info.daddr.u.extended_addr;
202	saddr = &info.saddr.u.extended_addr;
203
204	lowpan_header_compress(skb, dev, ETH_P_IPV6, daddr, saddr, skb->len);
205
206	cb->type = IEEE802154_FC_TYPE_DATA;
207
208	/* prepare wpan address data */
209	sa.mode = IEEE802154_ADDR_LONG;
210	sa.pan_id = ieee802154_mlme_ops(dev)->get_pan_id(dev);
211	sa.extended_addr = ieee802154_devaddr_from_raw(saddr);
212
213	/* intra-PAN communications */
214	da.pan_id = sa.pan_id;
215
216	/* if the destination address is the broadcast address, use the
217	 * corresponding short address
218	 */
219	if (lowpan_is_addr_broadcast((const u8 *)daddr)) {
220		da.mode = IEEE802154_ADDR_SHORT;
221		da.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
222		cb->ackreq = false;
223	} else {
224		da.mode = IEEE802154_ADDR_LONG;
225		da.extended_addr = ieee802154_devaddr_from_raw(daddr);
226		cb->ackreq = true;
227	}
228
229	return dev_hard_header(skb, lowpan_dev_info(dev)->real_dev,
230			ETH_P_IPV6, (void *)&da, (void *)&sa, 0);
231}
232
233netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *dev)
234{
235	struct ieee802154_hdr wpan_hdr;
236	int max_single, ret;
237
238	pr_debug("package xmit\n");
239
240	/* We must take a copy of the skb before we modify/replace the ipv6
241	 * header as the header could be used elsewhere
242	 */
243	skb = skb_unshare(skb, GFP_ATOMIC);
244	if (!skb)
245		return NET_XMIT_DROP;
246
247	ret = lowpan_header(skb, dev);
248	if (ret < 0) {
249		kfree_skb(skb);
250		return NET_XMIT_DROP;
251	}
252
253	if (ieee802154_hdr_peek(skb, &wpan_hdr) < 0) {
254		kfree_skb(skb);
255		return NET_XMIT_DROP;
256	}
257
258	max_single = ieee802154_max_payload(&wpan_hdr);
259
260	if (skb_tail_pointer(skb) - skb_network_header(skb) <= max_single) {
261		skb->dev = lowpan_dev_info(dev)->real_dev;
262		return dev_queue_xmit(skb);
263	} else {
264		netdev_tx_t rc;
265
266		pr_debug("frame is too big, fragmentation is needed\n");
267		rc = lowpan_xmit_fragmented(skb, dev, &wpan_hdr);
268
269		return rc < 0 ? NET_XMIT_DROP : rc;
270	}
271}
272