linux/net/phonet/pep-gprs.c
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   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: RĂ©mi 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
  37struct gprs_dev {
  38        struct sock             *sk;
  39        void                    (*old_state_change)(struct sock *);
  40        void                    (*old_data_ready)(struct sock *, int);
  41        void                    (*old_write_space)(struct sock *);
  42
  43        struct net_device       *dev;
  44};
  45
  46static __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
  64static 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
  76static 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
  88static 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
 141drop:
 142        if (skb) {
 143                dev_kfree_skb(skb);
 144                dev->stats.rx_dropped++;
 145        }
 146        return err;
 147}
 148
 149static void gprs_data_ready(struct sock *sk, int len)
 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
 160static 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
 172static 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
 180static int gprs_close(struct net_device *dev)
 181{
 182        netif_stop_queue(dev);
 183        return 0;
 184}
 185
 186static 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
 221static 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
 230static 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
 237static 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 */
 259int 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, 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
 307out_rel:
 308        release_sock(sk);
 309        unregister_netdev(dev);
 310        return err;
 311}
 312
 313void 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
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