Phonet: implement GPRS virtual interface over PEP socket

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 347 insertions, 0 deletions

diff --git a/net/phonet/pep-gprs.c b/net/phonet/pep-gprs.c
new file mode 100644
index 0000000..9978afb
--- /dev/null
+++ b/net/phonet/pep-gprs.c
@@ -0,0 +1,347 @@
+/*
+ * File: pep-gprs.c
+ *
+ * GPRS over Phonet pipe end point socket
+ *
+ * Copyright (C) 2008 Nokia Corporation.
+ *
+ * Author: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/if_ether.h>
+#include <linux/if_arp.h>
+#include <net/sock.h>
+
+#include <linux/if_phonet.h>
+#include <net/tcp_states.h>
+#include <net/phonet/gprs.h>
+
+#define GPRS_DEFAULT_MTU 1400
+
+struct gprs_dev {
+	struct sock		*sk;
+	void			(*old_state_change)(struct sock *);
+	void			(*old_data_ready)(struct sock *, int);
+	void			(*old_write_space)(struct sock *);
+
+	struct net_device	*net;
+	struct net_device_stats	stats;
+
+	struct sk_buff_head	tx_queue;
+	struct work_struct	tx_work;
+	spinlock_t		tx_lock;
+	unsigned		tx_max;
+};
+
+static int gprs_type_trans(struct sk_buff *skb)
+{
+	const u8 *pvfc;
+	u8 buf;
+
+	pvfc = skb_header_pointer(skb, 0, 1, &buf);
+	if (!pvfc)
+		return 0;
+	/* Look at IP version field */
+	switch (*pvfc >> 4) {
+	case 4:
+		return htons(ETH_P_IP);
+	case 6:
+		return htons(ETH_P_IPV6);
+	}
+	return 0;
+}
+
+/*
+ * Socket callbacks
+ */
+
+static void gprs_state_change(struct sock *sk)
+{
+	struct gprs_dev *dev = sk->sk_user_data;
+
+	if (sk->sk_state == TCP_CLOSE_WAIT) {
+		netif_stop_queue(dev->net);
+		netif_carrier_off(dev->net);
+	}
+}
+
+static int gprs_recv(struct gprs_dev *dev, struct sk_buff *skb)
+{
+	int err = 0;
+	u16 protocol = gprs_type_trans(skb);
+
+	if (!protocol) {
+		err = -EINVAL;
+		goto drop;
+	}
+
+	if (likely(skb_headroom(skb) & 3)) {
+		struct sk_buff *rskb, *fs;
+		int flen = 0;
+
+		/* Phonet Pipe data header is misaligned (3 bytes),
+		 * so wrap the IP packet as a single fragment of an head-less
+		 * socket buffer. The network stack will pull what it needs,
+		 * but at least, the whole IP payload is not memcpy'd. */
+		rskb = netdev_alloc_skb(dev->net, 0);
+		if (!rskb) {
+			err = -ENOBUFS;
+			goto drop;
+		}
+		skb_shinfo(rskb)->frag_list = skb;
+		rskb->len += skb->len;
+		rskb->data_len += rskb->len;
+		rskb->truesize += rskb->len;
+
+		/* Avoid nested fragments */
+		for (fs = skb_shinfo(skb)->frag_list; fs; fs = fs->next)
+			flen += fs->len;
+		skb->next = skb_shinfo(skb)->frag_list;
+		skb_shinfo(skb)->frag_list = NULL;
+		skb->len -= flen;
+		skb->data_len -= flen;
+		skb->truesize -= flen;
+
+		skb = rskb;
+	}
+
+	skb->protocol = protocol;
+	skb_reset_mac_header(skb);
+	skb->dev = dev->net;
+
+	if (likely(dev->net->flags & IFF_UP)) {
+		dev->stats.rx_packets++;
+		dev->stats.rx_bytes += skb->len;
+		netif_rx(skb);
+		skb = NULL;
+	} else
+		err = -ENODEV;
+
+drop:
+	if (skb) {
+		dev_kfree_skb(skb);
+		dev->stats.rx_dropped++;
+	}
+	return err;
+}
+
+static void gprs_data_ready(struct sock *sk, int len)
+{
+	struct gprs_dev *dev = sk->sk_user_data;
+	struct sk_buff *skb;
+
+	while ((skb = pep_read(sk)) != NULL) {
+		skb_orphan(skb);
+		gprs_recv(dev, skb);
+	}
+}
+
+static void gprs_write_space(struct sock *sk)
+{
+	struct gprs_dev *dev = sk->sk_user_data;
+	unsigned credits = pep_writeable(sk);
+
+	spin_lock_bh(&dev->tx_lock);
+	dev->tx_max = credits;
+	if (credits > skb_queue_len(&dev->tx_queue))
+		netif_wake_queue(dev->net);
+	spin_unlock_bh(&dev->tx_lock);
+}
+
+/*
+ * Network device callbacks
+ */
+
+static int gprs_xmit(struct sk_buff *skb, struct net_device *net)
+{
+	struct gprs_dev *dev = netdev_priv(net);
+
+	switch (skb->protocol) {
+	case  htons(ETH_P_IP):
+	case  htons(ETH_P_IPV6):
+		break;
+	default:
+		dev_kfree_skb(skb);
+		return 0;
+	}
+
+	spin_lock(&dev->tx_lock);
+	if (likely(skb_queue_len(&dev->tx_queue) < dev->tx_max)) {
+		skb_queue_tail(&dev->tx_queue, skb);
+		skb = NULL;
+	}
+	if (skb_queue_len(&dev->tx_queue) >= dev->tx_max)
+		netif_stop_queue(net);
+	spin_unlock(&dev->tx_lock);
+
+	schedule_work(&dev->tx_work);
+	if (unlikely(skb))
+		dev_kfree_skb(skb);
+	return 0;
+}
+
+static void gprs_tx(struct work_struct *work)
+{
+	struct gprs_dev *dev = container_of(work, struct gprs_dev, tx_work);
+	struct sock *sk = dev->sk;
+	struct sk_buff *skb;
+
+	while ((skb = skb_dequeue(&dev->tx_queue)) != NULL) {
+		int err;
+
+		dev->stats.tx_bytes += skb->len;
+		dev->stats.tx_packets++;
+
+		skb_orphan(skb);
+		skb_set_owner_w(skb, sk);
+
+		lock_sock(sk);
+		err = pep_write(sk, skb);
+		if (err) {
+			LIMIT_NETDEBUG(KERN_WARNING"%s: TX error (%d)\n",
+					dev->net->name, err);
+			dev->stats.tx_aborted_errors++;
+			dev->stats.tx_errors++;
+		}
+		release_sock(sk);
+	}
+
+	lock_sock(sk);
+	gprs_write_space(sk);
+	release_sock(sk);
+}
+
+static int gprs_set_mtu(struct net_device *net, int new_mtu)
+{
+	if ((new_mtu < 576) || (new_mtu > (PHONET_MAX_MTU - 11)))
+		return -EINVAL;
+
+	net->mtu = new_mtu;
+	return 0;
+}
+
+static struct net_device_stats *gprs_get_stats(struct net_device *net)
+{
+	struct gprs_dev *dev = netdev_priv(net);
+
+	return &dev->stats;
+}
+
+static void gprs_setup(struct net_device *net)
+{
+	net->features		= NETIF_F_FRAGLIST;
+	net->type		= ARPHRD_NONE;
+	net->flags		= IFF_POINTOPOINT | IFF_NOARP;
+	net->mtu		= GPRS_DEFAULT_MTU;
+	net->hard_header_len	= 0;
+	net->addr_len		= 0;
+	net->tx_queue_len	= 10;
+
+	net->destructor		= free_netdev;
+	net->hard_start_xmit	= gprs_xmit; /* mandatory */
+	net->change_mtu		= gprs_set_mtu;
+	net->get_stats		= gprs_get_stats;
+}
+
+/*
+ * External interface
+ */
+
+/*
+ * Attach a GPRS interface to a datagram socket.
+ * Returns the interface index on success, negative error code on error.
+ */
+int gprs_attach(struct sock *sk)
+{
+	static const char ifname[] = "gprs%d";
+	struct gprs_dev *dev;
+	struct net_device *net;
+	int err;
+
+	if (unlikely(sk->sk_type == SOCK_STREAM))
+		return -EINVAL; /* need packet boundaries */
+
+	/* Create net device */
+	net = alloc_netdev(sizeof(*dev), ifname, gprs_setup);
+	if (!net)
+		return -ENOMEM;
+	dev = netdev_priv(net);
+	dev->net = net;
+	dev->tx_max = 0;
+	spin_lock_init(&dev->tx_lock);
+	skb_queue_head_init(&dev->tx_queue);
+	INIT_WORK(&dev->tx_work, gprs_tx);
+
+	netif_stop_queue(net);
+	err = register_netdev(net);
+	if (err) {
+		free_netdev(net);
+		return err;
+	}
+
+	lock_sock(sk);
+	if (unlikely(sk->sk_user_data)) {
+		err = -EBUSY;
+		goto out_rel;
+	}
+	if (unlikely((1 << sk->sk_state & (TCPF_CLOSE|TCPF_LISTEN)) ||
+			sock_flag(sk, SOCK_DEAD))) {
+		err = -EINVAL;
+		goto out_rel;
+	}
+	sk->sk_user_data	= dev;
+	dev->old_state_change	= sk->sk_state_change;
+	dev->old_data_ready	= sk->sk_data_ready;
+	dev->old_write_space	= sk->sk_write_space;
+	sk->sk_state_change	= gprs_state_change;
+	sk->sk_data_ready	= gprs_data_ready;
+	sk->sk_write_space	= gprs_write_space;
+	release_sock(sk);
+
+	sock_hold(sk);
+	dev->sk = sk;
+
+	printk(KERN_DEBUG"%s: attached\n", net->name);
+	gprs_write_space(sk); /* kick off TX */
+	return net->ifindex;
+
+out_rel:
+	release_sock(sk);
+	unregister_netdev(net);
+	return err;
+}
+
+void gprs_detach(struct sock *sk)
+{
+	struct gprs_dev *dev = sk->sk_user_data;
+	struct net_device *net = dev->net;
+
+	lock_sock(sk);
+	sk->sk_user_data	= NULL;
+	sk->sk_state_change	= dev->old_state_change;
+	sk->sk_data_ready	= dev->old_data_ready;
+	sk->sk_write_space	= dev->old_write_space;
+	release_sock(sk);
+
+	printk(KERN_DEBUG"%s: detached\n", net->name);
+	unregister_netdev(net);
+	flush_scheduled_work();
+	sock_put(sk);
+	skb_queue_purge(&dev->tx_queue);
+}