/*
 * net/tipc/eth_media.c: Ethernet bearer support for TIPC
 *
 * Copyright (c) 2001-2007, Ericsson AB
 * Copyright (c) 2005-2007, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <net/tipc/tipc.h>
#include <net/tipc/tipc_bearer.h>
#include <net/tipc/tipc_msg.h>
#include <linux/netdevice.h>
#include <net/net_namespace.h>

#define MAX_ETH_BEARERS         2
#define ETH_LINK_PRIORITY       TIPC_DEF_LINK_PRI
#define ETH_LINK_TOLERANCE      TIPC_DEF_LINK_TOL
#define ETH_LINK_WINDOW         TIPC_DEF_LINK_WIN

/**
 * struct eth_bearer - Ethernet bearer data structure
 * @bearer: ptr to associated "generic" bearer structure
 * @dev: ptr to associated Ethernet network device
 * @tipc_packet_type: used in binding TIPC to Ethernet driver
 */

struct eth_bearer {
        struct tipc_bearer *bearer;
        struct net_device *dev;
        struct packet_type tipc_packet_type;
};

static struct eth_bearer eth_bearers[MAX_ETH_BEARERS];
static int eth_started = 0;
static struct notifier_block notifier;

/**
 * send_msg - send a TIPC message out over an Ethernet interface
 */

static int send_msg(struct sk_buff *buf, struct tipc_bearer *tb_ptr,
                    struct tipc_media_addr *dest)
{
        struct sk_buff *clone;
        struct net_device *dev;

        clone = skb_clone(buf, GFP_ATOMIC);
        if (clone) {
                skb_reset_network_header(clone);
                dev = ((struct eth_bearer *)(tb_ptr->usr_handle))->dev;
                clone->dev = dev;
                dev_hard_header(clone, dev, ETH_P_TIPC,
                                 &dest->dev_addr.eth_addr,
                                 dev->dev_addr, clone->len);
                dev_queue_xmit(clone);
        }
        return 0;
}

/**
 * recv_msg - handle incoming TIPC message from an Ethernet interface
 *
 * Accept only packets explicitly sent to this node, or broadcast packets;
 * ignores packets sent using Ethernet multicast, and traffic sent to other
 * nodes (which can happen if interface is running in promiscuous mode).
 * Routine truncates any Ethernet padding/CRC appended to the message,
 * and ensures message size matches actual length
 */

static int recv_msg(struct sk_buff *buf, struct net_device *dev,
                    struct packet_type *pt, struct net_device *orig_dev)
{
        struct eth_bearer *eb_ptr = (struct eth_bearer *)pt->af_packet_priv;
        u32 size;

        if (!net_eq(dev_net(dev), &init_net)) {
                kfree_skb(buf);
                return 0;
        }

        if (likely(eb_ptr->bearer)) {
                if (likely(buf->pkt_type <= PACKET_BROADCAST)) {
                        size = msg_size((struct tipc_msg *)buf->data);
                        skb_trim(buf, size);
                        if (likely(buf->len == size)) {
                                buf->next = NULL;
                                tipc_recv_msg(buf, eb_ptr->bearer);
                                return 0;
                        }
                }
        }
        kfree_skb(buf);
        return 0;
}

/**
 * enable_bearer - attach TIPC bearer to an Ethernet interface
 */

static int enable_bearer(struct tipc_bearer *tb_ptr)
{
        struct net_device *dev = NULL;
        struct net_device *pdev = NULL;
        struct eth_bearer *eb_ptr = &eth_bearers[0];
        struct eth_bearer *stop = &eth_bearers[MAX_ETH_BEARERS];
        char *driver_name = strchr((const char *)tb_ptr->name, ':') + 1;

        /* Find device with specified name */

        for_each_netdev(&init_net, pdev){
                if (!strncmp(pdev->name, driver_name, IFNAMSIZ)) {
                        dev = pdev;
                        break;
                }
        }
        if (!dev)
                return -ENODEV;

        /* Find Ethernet bearer for device (or create one) */

        for (;(eb_ptr != stop) && eb_ptr->dev && (eb_ptr->dev != dev); eb_ptr++);
        if (eb_ptr == stop)
                return -EDQUOT;
        if (!eb_ptr->dev) {
                eb_ptr->dev = dev;
                eb_ptr->tipc_packet_type.type = htons(ETH_P_TIPC);
                eb_ptr->tipc_packet_type.dev = dev;
                eb_ptr->tipc_packet_type.func = recv_msg;
                eb_ptr->tipc_packet_type.af_packet_priv = eb_ptr;
                INIT_LIST_HEAD(&(eb_ptr->tipc_packet_type.list));
                dev_hold(dev);
                dev_add_pack(&eb_ptr->tipc_packet_type);
        }

        /* Associate TIPC bearer with Ethernet bearer */

        eb_ptr->bearer = tb_ptr;
        tb_ptr->usr_handle = (void *)eb_ptr;
        tb_ptr->mtu = dev->mtu;
        tb_ptr->blocked = 0;
        tb_ptr->addr.type = htonl(TIPC_MEDIA_TYPE_ETH);
        memcpy(&tb_ptr->addr.dev_addr, dev->dev_addr, ETH_ALEN);
        return 0;
}

/**
 * disable_bearer - detach TIPC bearer from an Ethernet interface
 *
 * We really should do dev_remove_pack() here, but this function can not be
 * called at tasklet level. => Use eth_bearer->bearer as a flag to throw away
 * incoming buffers, & postpone dev_remove_pack() to eth_media_stop() on exit.
 */

static void disable_bearer(struct tipc_bearer *tb_ptr)
{
        ((struct eth_bearer *)tb_ptr->usr_handle)->bearer = NULL;
}

/**
 * recv_notification - handle device updates from OS
 *
 * Change the state of the Ethernet bearer (if any) associated with the
 * specified device.
 */

static int recv_notification(struct notifier_block *nb, unsigned long evt,
                             void *dv)
{
        struct net_device *dev = (struct net_device *)dv;
        struct eth_bearer *eb_ptr = &eth_bearers[0];
        struct eth_bearer *stop = &eth_bearers[MAX_ETH_BEARERS];

        if (!net_eq(dev_net(dev), &init_net))
                return NOTIFY_DONE;

        while ((eb_ptr->dev != dev)) {
                if (++eb_ptr == stop)
                        return NOTIFY_DONE;     /* couldn't find device */
        }
        if (!eb_ptr->bearer)
                return NOTIFY_DONE;             /* bearer had been disabled */

        eb_ptr->bearer->mtu = dev->mtu;

        switch (evt) {
        case NETDEV_CHANGE:
                if (netif_carrier_ok(dev))
                        tipc_continue(eb_ptr->bearer);
                else
                        tipc_block_bearer(eb_ptr->bearer->name);
                break;
        case NETDEV_UP:
                tipc_continue(eb_ptr->bearer);
                break;
        case NETDEV_DOWN:
                tipc_block_bearer(eb_ptr->bearer->name);
                break;
        case NETDEV_CHANGEMTU:
        case NETDEV_CHANGEADDR:
                tipc_block_bearer(eb_ptr->bearer->name);
                tipc_continue(eb_ptr->bearer);
                break;
        case NETDEV_UNREGISTER:
        case NETDEV_CHANGENAME:
                tipc_disable_bearer(eb_ptr->bearer->name);
                break;
        }
        return NOTIFY_OK;
}

/**
 * eth_addr2str - convert Ethernet address to string
 */

static char *eth_addr2str(struct tipc_media_addr *a, char *str_buf, int str_size)
{
        unchar *addr = (unchar *)&a->dev_addr;

        if (str_size < 18)
                *str_buf = '\0';
        else
                sprintf(str_buf, "%pM", addr);
        return str_buf;
}

/**
 * tipc_eth_media_start - activate Ethernet bearer support
 *
 * Register Ethernet media type with TIPC bearer code.  Also register
 * with OS for notifications about device state changes.
 */

int tipc_eth_media_start(void)
{
        struct tipc_media_addr bcast_addr;
        int res;

        if (eth_started)
                return -EINVAL;

        bcast_addr.type = htonl(TIPC_MEDIA_TYPE_ETH);
        memset(&bcast_addr.dev_addr, 0xff, ETH_ALEN);

        memset(eth_bearers, 0, sizeof(eth_bearers));

        res = tipc_register_media(TIPC_MEDIA_TYPE_ETH, "eth",
                                  enable_bearer, disable_bearer, send_msg,
                                  eth_addr2str, &bcast_addr, ETH_LINK_PRIORITY,
                                  ETH_LINK_TOLERANCE, ETH_LINK_WINDOW);
        if (res)
                return res;

        notifier.notifier_call = &recv_notification;
        notifier.priority = 0;
        res = register_netdevice_notifier(&notifier);
        if (!res)
                eth_started = 1;
        return res;
}

/**
 * tipc_eth_media_stop - deactivate Ethernet bearer support
 */

void tipc_eth_media_stop(void)
{
        int i;

        if (!eth_started)
                return;

        unregister_netdevice_notifier(&notifier);
        for (i = 0; i < MAX_ETH_BEARERS ; i++) {
                if (eth_bearers[i].bearer) {
                        eth_bearers[i].bearer->blocked = 1;
                        eth_bearers[i].bearer = NULL;
                }
                if (eth_bearers[i].dev) {
                        dev_remove_pack(&eth_bearers[i].tipc_packet_type);
                        dev_put(eth_bearers[i].dev);
                }
        }
        memset(&eth_bearers, 0, sizeof(eth_bearers));
        eth_started = 0;
}