#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/if_vlan.h>
#include <linux/netpoll.h>
#include "vlan.h"

bool vlan_do_receive(struct sk_buff **skbp)
{
        struct sk_buff *skb = *skbp;
        u16 vlan_id = skb->vlan_tci & VLAN_VID_MASK;
        struct net_device *vlan_dev;
        struct vlan_pcpu_stats *rx_stats;

        vlan_dev = vlan_find_dev(skb->dev, vlan_id);
        if (!vlan_dev) {
                if (vlan_id)
                        skb->pkt_type = PACKET_OTHERHOST;
                return false;
        }

        skb = *skbp = skb_share_check(skb, GFP_ATOMIC);
        if (unlikely(!skb))
                return false;

        skb->dev = vlan_dev;
        if (skb->pkt_type == PACKET_OTHERHOST) {
                /* Our lower layer thinks this is not local, let's make sure.
                 * This allows the VLAN to have a different MAC than the
                 * underlying device, and still route correctly. */
                if (!compare_ether_addr(eth_hdr(skb)->h_dest,
                                        vlan_dev->dev_addr))
                        skb->pkt_type = PACKET_HOST;
        }

        if (!(vlan_dev_info(vlan_dev)->flags & VLAN_FLAG_REORDER_HDR)) {
                unsigned int offset = skb->data - skb_mac_header(skb);

                /*
                 * vlan_insert_tag expect skb->data pointing to mac header.
                 * So change skb->data before calling it and change back to
                 * original position later
                 */
                skb_push(skb, offset);
                skb = *skbp = vlan_insert_tag(skb, skb->vlan_tci);
                if (!skb)
                        return false;
                skb_pull(skb, offset + VLAN_HLEN);
                skb_reset_mac_len(skb);
        }

        skb->priority = vlan_get_ingress_priority(vlan_dev, skb->vlan_tci);
        skb->vlan_tci = 0;

        rx_stats = this_cpu_ptr(vlan_dev_info(vlan_dev)->vlan_pcpu_stats);

        u64_stats_update_begin(&rx_stats->syncp);
        rx_stats->rx_packets++;
        rx_stats->rx_bytes += skb->len;
        if (skb->pkt_type == PACKET_MULTICAST)
                rx_stats->rx_multicast++;
        u64_stats_update_end(&rx_stats->syncp);

        return true;
}

/* Must be invoked with rcu_read_lock or with RTNL. */
struct net_device *__vlan_find_dev_deep(struct net_device *real_dev,
                                        u16 vlan_id)
{
        struct vlan_group *grp = rcu_dereference_rtnl(real_dev->vlgrp);

        if (grp) {
                return vlan_group_get_device(grp, vlan_id);
        } else {
                /*
                 * Bonding slaves do not have grp assigned to themselves.
                 * Grp is assigned to bonding master instead.
                 */
                if (netif_is_bond_slave(real_dev))
                        return __vlan_find_dev_deep(real_dev->master, vlan_id);
        }

        return NULL;
}
EXPORT_SYMBOL(__vlan_find_dev_deep);

struct net_device *vlan_dev_real_dev(const struct net_device *dev)
{
        return vlan_dev_info(dev)->real_dev;
}
EXPORT_SYMBOL(vlan_dev_real_dev);

u16 vlan_dev_vlan_id(const struct net_device *dev)
{
        return vlan_dev_info(dev)->vlan_id;
}
EXPORT_SYMBOL(vlan_dev_vlan_id);

static struct sk_buff *vlan_reorder_header(struct sk_buff *skb)
{
        if (skb_cow(skb, skb_headroom(skb)) < 0)
                return NULL;
        memmove(skb->data - ETH_HLEN, skb->data - VLAN_ETH_HLEN, 2 * ETH_ALEN);
        skb->mac_header += VLAN_HLEN;
        skb_reset_mac_len(skb);
        return skb;
}

static void vlan_set_encap_proto(struct sk_buff *skb, struct vlan_hdr *vhdr)
{
        __be16 proto;
        unsigned char *rawp;

        /*
         * Was a VLAN packet, grab the encapsulated protocol, which the layer
         * three protocols care about.
         */

        proto = vhdr->h_vlan_encapsulated_proto;
        if (ntohs(proto) >= 1536) {
                skb->protocol = proto;
                return;
        }

        rawp = skb->data;
        if (*(unsigned short *) rawp == 0xFFFF)
                /*
                 * This is a magic hack to spot IPX packets. Older Novell
                 * breaks the protocol design and runs IPX over 802.3 without
                 * an 802.2 LLC layer. We look for FFFF which isn't a used
                 * 802.2 SSAP/DSAP. This won't work for fault tolerant netware
                 * but does for the rest.
                 */
                skb->protocol = htons(ETH_P_802_3);
        else
                /*
                 * Real 802.2 LLC
                 */
                skb->protocol = htons(ETH_P_802_2);
}

struct sk_buff *vlan_untag(struct sk_buff *skb)
{
        struct vlan_hdr *vhdr;
        u16 vlan_tci;

        if (unlikely(vlan_tx_tag_present(skb))) {
                /* vlan_tci is already set-up so leave this for another time */
                return skb;
        }

        skb = skb_share_check(skb, GFP_ATOMIC);
        if (unlikely(!skb))
                goto err_free;

        if (unlikely(!pskb_may_pull(skb, VLAN_HLEN)))
                goto err_free;

        vhdr = (struct vlan_hdr *) skb->data;
        vlan_tci = ntohs(vhdr->h_vlan_TCI);
        __vlan_hwaccel_put_tag(skb, vlan_tci);

        skb_pull_rcsum(skb, VLAN_HLEN);
        vlan_set_encap_proto(skb, vhdr);

        skb = vlan_reorder_header(skb);
        if (unlikely(!skb))
                goto err_free;

        skb_reset_network_header(skb);
        skb_reset_transport_header(skb);
        return skb;

err_free:
        kfree_skb(skb);
        return NULL;
}