1 /*
2 * File: pep-gprs.c
3 *
4 * GPRS over Phonet pipe end point socket
5 *
6 * Copyright (C) 2008 Nokia Corporation.
7 *
8 * Author: Rémi Denis-Courmont
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * version 2 as published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA
23 */
24
25 #include <linux/kernel.h>
26 #include <linux/netdevice.h>
27 #include <linux/if_ether.h>
28 #include <linux/if_arp.h>
29 #include <net/sock.h>
30
31 #include <linux/if_phonet.h>
32 #include <net/tcp_states.h>
33 #include <net/phonet/gprs.h>
34
35 #define GPRS_DEFAULT_MTU 1400
36
37 struct gprs_dev {
38 struct sock *sk;
39 void (*old_state_change)(struct sock *);
40 void (*old_data_ready)(struct sock *);
41 void (*old_write_space)(struct sock *);
42
43 struct net_device *dev;
44 };
45
gprs_type_trans(struct sk_buff * skb)46 static __be16 gprs_type_trans(struct sk_buff *skb)
47 {
48 const u8 *pvfc;
49 u8 buf;
50
51 pvfc = skb_header_pointer(skb, 0, 1, &buf);
52 if (!pvfc)
53 return htons(0);
54 /* Look at IP version field */
55 switch (*pvfc >> 4) {
56 case 4:
57 return htons(ETH_P_IP);
58 case 6:
59 return htons(ETH_P_IPV6);
60 }
61 return htons(0);
62 }
63
gprs_writeable(struct gprs_dev * gp)64 static void gprs_writeable(struct gprs_dev *gp)
65 {
66 struct net_device *dev = gp->dev;
67
68 if (pep_writeable(gp->sk))
69 netif_wake_queue(dev);
70 }
71
72 /*
73 * Socket callbacks
74 */
75
gprs_state_change(struct sock * sk)76 static void gprs_state_change(struct sock *sk)
77 {
78 struct gprs_dev *gp = sk->sk_user_data;
79
80 if (sk->sk_state == TCP_CLOSE_WAIT) {
81 struct net_device *dev = gp->dev;
82
83 netif_stop_queue(dev);
84 netif_carrier_off(dev);
85 }
86 }
87
gprs_recv(struct gprs_dev * gp,struct sk_buff * skb)88 static int gprs_recv(struct gprs_dev *gp, struct sk_buff *skb)
89 {
90 struct net_device *dev = gp->dev;
91 int err = 0;
92 __be16 protocol = gprs_type_trans(skb);
93
94 if (!protocol) {
95 err = -EINVAL;
96 goto drop;
97 }
98
99 if (skb_headroom(skb) & 3) {
100 struct sk_buff *rskb, *fs;
101 int flen = 0;
102
103 /* Phonet Pipe data header may be misaligned (3 bytes),
104 * so wrap the IP packet as a single fragment of an head-less
105 * socket buffer. The network stack will pull what it needs,
106 * but at least, the whole IP payload is not memcpy'd. */
107 rskb = netdev_alloc_skb(dev, 0);
108 if (!rskb) {
109 err = -ENOBUFS;
110 goto drop;
111 }
112 skb_shinfo(rskb)->frag_list = skb;
113 rskb->len += skb->len;
114 rskb->data_len += rskb->len;
115 rskb->truesize += rskb->len;
116
117 /* Avoid nested fragments */
118 skb_walk_frags(skb, fs)
119 flen += fs->len;
120 skb->next = skb_shinfo(skb)->frag_list;
121 skb_frag_list_init(skb);
122 skb->len -= flen;
123 skb->data_len -= flen;
124 skb->truesize -= flen;
125
126 skb = rskb;
127 }
128
129 skb->protocol = protocol;
130 skb_reset_mac_header(skb);
131 skb->dev = dev;
132
133 if (likely(dev->flags & IFF_UP)) {
134 dev->stats.rx_packets++;
135 dev->stats.rx_bytes += skb->len;
136 netif_rx(skb);
137 skb = NULL;
138 } else
139 err = -ENODEV;
140
141 drop:
142 if (skb) {
143 dev_kfree_skb(skb);
144 dev->stats.rx_dropped++;
145 }
146 return err;
147 }
148
gprs_data_ready(struct sock * sk)149 static void gprs_data_ready(struct sock *sk)
150 {
151 struct gprs_dev *gp = sk->sk_user_data;
152 struct sk_buff *skb;
153
154 while ((skb = pep_read(sk)) != NULL) {
155 skb_orphan(skb);
156 gprs_recv(gp, skb);
157 }
158 }
159
gprs_write_space(struct sock * sk)160 static void gprs_write_space(struct sock *sk)
161 {
162 struct gprs_dev *gp = sk->sk_user_data;
163
164 if (netif_running(gp->dev))
165 gprs_writeable(gp);
166 }
167
168 /*
169 * Network device callbacks
170 */
171
gprs_open(struct net_device * dev)172 static int gprs_open(struct net_device *dev)
173 {
174 struct gprs_dev *gp = netdev_priv(dev);
175
176 gprs_writeable(gp);
177 return 0;
178 }
179
gprs_close(struct net_device * dev)180 static int gprs_close(struct net_device *dev)
181 {
182 netif_stop_queue(dev);
183 return 0;
184 }
185
gprs_xmit(struct sk_buff * skb,struct net_device * dev)186 static netdev_tx_t gprs_xmit(struct sk_buff *skb, struct net_device *dev)
187 {
188 struct gprs_dev *gp = netdev_priv(dev);
189 struct sock *sk = gp->sk;
190 int len, err;
191
192 switch (skb->protocol) {
193 case htons(ETH_P_IP):
194 case htons(ETH_P_IPV6):
195 break;
196 default:
197 dev_kfree_skb(skb);
198 return NETDEV_TX_OK;
199 }
200
201 skb_orphan(skb);
202 skb_set_owner_w(skb, sk);
203 len = skb->len;
204 err = pep_write(sk, skb);
205 if (err) {
206 LIMIT_NETDEBUG(KERN_WARNING"%s: TX error (%d)\n",
207 dev->name, err);
208 dev->stats.tx_aborted_errors++;
209 dev->stats.tx_errors++;
210 } else {
211 dev->stats.tx_packets++;
212 dev->stats.tx_bytes += len;
213 }
214
215 netif_stop_queue(dev);
216 if (pep_writeable(sk))
217 netif_wake_queue(dev);
218 return NETDEV_TX_OK;
219 }
220
gprs_set_mtu(struct net_device * dev,int new_mtu)221 static int gprs_set_mtu(struct net_device *dev, int new_mtu)
222 {
223 if ((new_mtu < 576) || (new_mtu > (PHONET_MAX_MTU - 11)))
224 return -EINVAL;
225
226 dev->mtu = new_mtu;
227 return 0;
228 }
229
230 static const struct net_device_ops gprs_netdev_ops = {
231 .ndo_open = gprs_open,
232 .ndo_stop = gprs_close,
233 .ndo_start_xmit = gprs_xmit,
234 .ndo_change_mtu = gprs_set_mtu,
235 };
236
gprs_setup(struct net_device * dev)237 static void gprs_setup(struct net_device *dev)
238 {
239 dev->features = NETIF_F_FRAGLIST;
240 dev->type = ARPHRD_PHONET_PIPE;
241 dev->flags = IFF_POINTOPOINT | IFF_NOARP;
242 dev->mtu = GPRS_DEFAULT_MTU;
243 dev->hard_header_len = 0;
244 dev->addr_len = 0;
245 dev->tx_queue_len = 10;
246
247 dev->netdev_ops = &gprs_netdev_ops;
248 dev->destructor = free_netdev;
249 }
250
251 /*
252 * External interface
253 */
254
255 /*
256 * Attach a GPRS interface to a datagram socket.
257 * Returns the interface index on success, negative error code on error.
258 */
gprs_attach(struct sock * sk)259 int gprs_attach(struct sock *sk)
260 {
261 static const char ifname[] = "gprs%d";
262 struct gprs_dev *gp;
263 struct net_device *dev;
264 int err;
265
266 if (unlikely(sk->sk_type == SOCK_STREAM))
267 return -EINVAL; /* need packet boundaries */
268
269 /* Create net device */
270 dev = alloc_netdev(sizeof(*gp), ifname, NET_NAME_UNKNOWN, gprs_setup);
271 if (!dev)
272 return -ENOMEM;
273 gp = netdev_priv(dev);
274 gp->sk = sk;
275 gp->dev = dev;
276
277 netif_stop_queue(dev);
278 err = register_netdev(dev);
279 if (err) {
280 free_netdev(dev);
281 return err;
282 }
283
284 lock_sock(sk);
285 if (unlikely(sk->sk_user_data)) {
286 err = -EBUSY;
287 goto out_rel;
288 }
289 if (unlikely((1 << sk->sk_state & (TCPF_CLOSE|TCPF_LISTEN)) ||
290 sock_flag(sk, SOCK_DEAD))) {
291 err = -EINVAL;
292 goto out_rel;
293 }
294 sk->sk_user_data = gp;
295 gp->old_state_change = sk->sk_state_change;
296 gp->old_data_ready = sk->sk_data_ready;
297 gp->old_write_space = sk->sk_write_space;
298 sk->sk_state_change = gprs_state_change;
299 sk->sk_data_ready = gprs_data_ready;
300 sk->sk_write_space = gprs_write_space;
301 release_sock(sk);
302 sock_hold(sk);
303
304 printk(KERN_DEBUG"%s: attached\n", dev->name);
305 return dev->ifindex;
306
307 out_rel:
308 release_sock(sk);
309 unregister_netdev(dev);
310 return err;
311 }
312
gprs_detach(struct sock * sk)313 void gprs_detach(struct sock *sk)
314 {
315 struct gprs_dev *gp = sk->sk_user_data;
316 struct net_device *dev = gp->dev;
317
318 lock_sock(sk);
319 sk->sk_user_data = NULL;
320 sk->sk_state_change = gp->old_state_change;
321 sk->sk_data_ready = gp->old_data_ready;
322 sk->sk_write_space = gp->old_write_space;
323 release_sock(sk);
324
325 printk(KERN_DEBUG"%s: detached\n", dev->name);
326 unregister_netdev(dev);
327 sock_put(sk);
328 }
329