/* Copyright 2011-2014 Autronica Fire and Security AS
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * Author(s):
 *      2011-2014 Arvid Brodin, arvid.brodin@alten.se
 */

#include "hsr_slave.h"
#include <linux/etherdevice.h>
#include <linux/if_arp.h>
#include <linux/if_vlan.h>
#include "hsr_main.h"
#include "hsr_device.h"
#include "hsr_forward.h"
#include "hsr_framereg.h"


static rx_handler_result_t hsr_handle_frame(struct sk_buff **pskb)
{
        struct sk_buff *skb = *pskb;
        struct hsr_port *port;
        u16 protocol;

        if (!skb_mac_header_was_set(skb)) {
                WARN_ONCE(1, "%s: skb invalid", __func__);
                return RX_HANDLER_PASS;
        }

        rcu_read_lock(); /* hsr->node_db, hsr->ports */
        port = hsr_port_get_rcu(skb->dev);

        if (hsr_addr_is_self(port->hsr, eth_hdr(skb)->h_source)) {
                /* Directly kill frames sent by ourselves */
                kfree_skb(skb);
                goto finish_consume;
        }

        protocol = eth_hdr(skb)->h_proto;
        if (protocol != htons(ETH_P_PRP) && protocol != htons(ETH_P_HSR))
                goto finish_pass;

        skb_push(skb, ETH_HLEN);

        hsr_forward_skb(skb, port);

finish_consume:
        rcu_read_unlock(); /* hsr->node_db, hsr->ports */
        return RX_HANDLER_CONSUMED;

finish_pass:
        rcu_read_unlock(); /* hsr->node_db, hsr->ports */
        return RX_HANDLER_PASS;
}

bool hsr_port_exists(const struct net_device *dev)
{
        return rcu_access_pointer(dev->rx_handler) == hsr_handle_frame;
}


static int hsr_check_dev_ok(struct net_device *dev)
{
        /* Don't allow HSR on non-ethernet like devices */
        if ((dev->flags & IFF_LOOPBACK) || (dev->type != ARPHRD_ETHER) ||
            (dev->addr_len != ETH_ALEN)) {
                netdev_info(dev, "Cannot use loopback or non-ethernet device as HSR slave.\n");
                return -EINVAL;
        }

        /* Don't allow enslaving hsr devices */
        if (is_hsr_master(dev)) {
                netdev_info(dev, "Cannot create trees of HSR devices.\n");
                return -EINVAL;
        }

        if (hsr_port_exists(dev)) {
                netdev_info(dev, "This device is already a HSR slave.\n");
                return -EINVAL;
        }

        if (is_vlan_dev(dev)) {
                netdev_info(dev, "HSR on top of VLAN is not yet supported in this driver.\n");
                return -EINVAL;
        }

        if (dev->priv_flags & IFF_DONT_BRIDGE) {
                netdev_info(dev, "This device does not support bridging.\n");
                return -EOPNOTSUPP;
        }

        /* HSR over bonded devices has not been tested, but I'm not sure it
         * won't work...
         */

        return 0;
}


/* Setup device to be added to the HSR bridge. */
static int hsr_portdev_setup(struct net_device *dev, struct hsr_port *port)
{
        int res;

        dev_hold(dev);
        res = dev_set_promiscuity(dev, 1);
        if (res)
                goto fail_promiscuity;

        /* FIXME:
         * What does net device "adjacency" mean? Should we do
         * res = netdev_master_upper_dev_link(port->dev, port->hsr->dev); ?
         */

        res = netdev_rx_handler_register(dev, hsr_handle_frame, port);
        if (res)
                goto fail_rx_handler;
        dev_disable_lro(dev);

        return 0;

fail_rx_handler:
        dev_set_promiscuity(dev, -1);
fail_promiscuity:
        dev_put(dev);

        return res;
}

int hsr_add_port(struct hsr_priv *hsr, struct net_device *dev,
                 enum hsr_port_type type)
{
        struct hsr_port *port, *master;
        int res;

        if (type != HSR_PT_MASTER) {
                res = hsr_check_dev_ok(dev);
                if (res)
                        return res;
        }

        port = hsr_port_get_hsr(hsr, type);
        if (port != NULL)
                return -EBUSY;  /* This port already exists */

        port = kzalloc(sizeof(*port), GFP_KERNEL);
        if (port == NULL)
                return -ENOMEM;

        if (type != HSR_PT_MASTER) {
                res = hsr_portdev_setup(dev, port);
                if (res)
                        goto fail_dev_setup;
        }

        port->hsr = hsr;
        port->dev = dev;
        port->type = type;

        list_add_tail_rcu(&port->port_list, &hsr->ports);
        synchronize_rcu();

        master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
        netdev_update_features(master->dev);
        dev_set_mtu(master->dev, hsr_get_max_mtu(hsr));

        return 0;

fail_dev_setup:
        kfree(port);
        return res;
}

void hsr_del_port(struct hsr_port *port)
{
        struct hsr_priv *hsr;
        struct hsr_port *master;

        hsr = port->hsr;
        master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
        list_del_rcu(&port->port_list);

        if (port != master) {
                if (master != NULL) {
                        netdev_update_features(master->dev);
                        dev_set_mtu(master->dev, hsr_get_max_mtu(hsr));
                }
                netdev_rx_handler_unregister(port->dev);
                dev_set_promiscuity(port->dev, -1);
        }

        /* FIXME?
         * netdev_upper_dev_unlink(port->dev, port->hsr->dev);
         */

        synchronize_rcu();

        if (port != master)
                dev_put(port->dev);
}