/*
 * net/tipc/eth_media.c: Ethernet bearer support for TIPC
 *
 * Copyright (c) 2001-2007, Ericsson AB
 * Copyright (c) 2005-2008, 2011, 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 "core.h"
#include "bearer.h"

#define MAX_ETH_BEARERS         MAX_BEARERS

#define ETH_ADDR_OFFSET 4       /* message header offset of MAC address */

/**
 * 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
 * @setup: work item used when enabling bearer
 * @cleanup: work item used when disabling bearer
 */
struct eth_bearer {
        struct tipc_bearer *bearer;
        struct net_device *dev;
        struct packet_type tipc_packet_type;
        struct work_struct setup;
        struct work_struct cleanup;
};

static struct tipc_media eth_media_info;
static struct eth_bearer eth_bearers[MAX_ETH_BEARERS];
static int eth_started;

static int recv_notification(struct notifier_block *nb, unsigned long evt,
                              void *dv);
/*
 * Network device notifier info
 */
static struct notifier_block notifier = {
        .notifier_call  = recv_notification,
        .priority       = 0
};

/**
 * eth_media_addr_set - initialize Ethernet media address structure
 *
 * Media-dependent "value" field stores MAC address in first 6 bytes
 * and zeroes out the remaining bytes.
 */
static void eth_media_addr_set(const struct tipc_bearer *tb_ptr,
                               struct tipc_media_addr *a, char *mac)
{
        memcpy(a->value, mac, ETH_ALEN);
        memset(a->value + ETH_ALEN, 0, sizeof(a->value) - ETH_ALEN);
        a->media_id = TIPC_MEDIA_TYPE_ETH;
        a->broadcast = !memcmp(mac, tb_ptr->bcast_addr.value, ETH_ALEN);
}

/**
 * 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;
        int delta;

        clone = skb_clone(buf, GFP_ATOMIC);
        if (!clone)
                return 0;

        dev = ((struct eth_bearer *)(tb_ptr->usr_handle))->dev;
        delta = dev->hard_header_len - skb_headroom(buf);

        if ((delta > 0) &&
            pskb_expand_head(clone, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
                kfree_skb(clone);
                return 0;
        }

        skb_reset_network_header(clone);
        clone->dev = dev;
        clone->protocol = htons(ETH_P_TIPC);
        dev_hard_header(clone, dev, ETH_P_TIPC, dest->value,
                        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).
 */
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;

        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)) {
                        buf->next = NULL;
                        tipc_recv_msg(buf, eb_ptr->bearer);
                        return 0;
                }
        }
        kfree_skb(buf);
        return 0;
}

/**
 * setup_bearer - setup association between Ethernet bearer and interface
 */
static void setup_bearer(struct work_struct *work)
{
        struct eth_bearer *eb_ptr =
                container_of(work, struct eth_bearer, setup);

        dev_add_pack(&eb_ptr->tipc_packet_type);
}

/**
 * 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;
        int pending_dev = 0;

        /* Find unused Ethernet bearer structure */
        while (eb_ptr->dev) {
                if (!eb_ptr->bearer)
                        pending_dev++;
                if (++eb_ptr == stop)
                        return pending_dev ? -EAGAIN : -EDQUOT;
        }

        /* Find device with specified name */
        read_lock(&dev_base_lock);
        for_each_netdev(&init_net, pdev) {
                if (!strncmp(pdev->name, driver_name, IFNAMSIZ)) {
                        dev = pdev;
                        dev_hold(dev);
                        break;
                }
        }
        read_unlock(&dev_base_lock);
        if (!dev)
                return -ENODEV;

        /* Create Ethernet bearer for device */
        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));
        INIT_WORK(&eb_ptr->setup, setup_bearer);
        schedule_work(&eb_ptr->setup);

        /* Associate TIPC bearer with Ethernet bearer */
        eb_ptr->bearer = tb_ptr;
        tb_ptr->usr_handle = (void *)eb_ptr;
        memset(tb_ptr->bcast_addr.value, 0, sizeof(tb_ptr->bcast_addr.value));
        memcpy(tb_ptr->bcast_addr.value, dev->broadcast, ETH_ALEN);
        tb_ptr->bcast_addr.media_id = TIPC_MEDIA_TYPE_ETH;
        tb_ptr->bcast_addr.broadcast = 1;
        tb_ptr->mtu = dev->mtu;
        tb_ptr->blocked = 0;
        eth_media_addr_set(tb_ptr, &tb_ptr->addr, (char *)dev->dev_addr);
        return 0;
}

/**
 * cleanup_bearer - break association between Ethernet bearer and interface
 *
 * This routine must be invoked from a work queue because it can sleep.
 */
static void cleanup_bearer(struct work_struct *work)
{
        struct eth_bearer *eb_ptr =
                container_of(work, struct eth_bearer, cleanup);

        dev_remove_pack(&eb_ptr->tipc_packet_type);
        dev_put(eb_ptr->dev);
        eb_ptr->dev = NULL;
}

/**
 * disable_bearer - detach TIPC bearer from an Ethernet interface
 *
 * Mark Ethernet bearer as inactive so that incoming buffers are thrown away,
 * then get worker thread to complete bearer cleanup.  (Can't do cleanup
 * here because cleanup code needs to sleep and caller holds spinlocks.)
 */
static void disable_bearer(struct tipc_bearer *tb_ptr)
{
        struct eth_bearer *eb_ptr = (struct eth_bearer *)tb_ptr->usr_handle;

        eb_ptr->bearer = NULL;
        INIT_WORK(&eb_ptr->cleanup, cleanup_bearer);
        schedule_work(&eb_ptr->cleanup);
}

/**
 * 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 int eth_addr2str(struct tipc_media_addr *a, char *str_buf, int str_size)
{
        if (str_size < 18)      /* 18 = strlen("aa:bb:cc:dd:ee:ff\0") */
                return 1;

        sprintf(str_buf, "%pM", a->value);
        return 0;
}

/**
 * eth_str2addr - convert Ethernet address format to message header format
 */
static int eth_addr2msg(struct tipc_media_addr *a, char *msg_area)
{
        memset(msg_area, 0, TIPC_MEDIA_ADDR_SIZE);
        msg_area[TIPC_MEDIA_TYPE_OFFSET] = TIPC_MEDIA_TYPE_ETH;
        memcpy(msg_area + ETH_ADDR_OFFSET, a->value, ETH_ALEN);
        return 0;
}

/**
 * eth_str2addr - convert message header address format to Ethernet format
 */
static int eth_msg2addr(const struct tipc_bearer *tb_ptr,
                        struct tipc_media_addr *a, char *msg_area)
{
        if (msg_area[TIPC_MEDIA_TYPE_OFFSET] != TIPC_MEDIA_TYPE_ETH)
                return 1;

        eth_media_addr_set(tb_ptr, a, msg_area + ETH_ADDR_OFFSET);
        return 0;
}

/*
 * Ethernet media registration info
 */
static struct tipc_media eth_media_info = {
        .send_msg       = send_msg,
        .enable_bearer  = enable_bearer,
        .disable_bearer = disable_bearer,
        .addr2str       = eth_addr2str,
        .addr2msg       = eth_addr2msg,
        .msg2addr       = eth_msg2addr,
        .priority       = TIPC_DEF_LINK_PRI,
        .tolerance      = TIPC_DEF_LINK_TOL,
        .window         = TIPC_DEF_LINK_WIN,
        .type_id        = TIPC_MEDIA_TYPE_ETH,
        .name           = "eth"
};

/**
 * 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)
{
        int res;

        if (eth_started)
                return -EINVAL;

        res = tipc_register_media(&eth_media_info);
        if (res)
                return res;

        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)
{
        if (!eth_started)
                return;

        flush_scheduled_work();
        unregister_netdevice_notifier(&notifier);
        eth_started = 0;
}