/*
 * Copyright (c) 2007-2011 Nicira Networks.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License 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 Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

#include "flow.h"
#include "datapath.h"
#include <linux/uaccess.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <net/llc_pdu.h>
#include <linux/kernel.h>
#include <linux/jhash.h>
#include <linux/jiffies.h>
#include <linux/llc.h>
#include <linux/module.h>
#include <linux/in.h>
#include <linux/rcupdate.h>
#include <linux/if_arp.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/icmp.h>
#include <linux/icmpv6.h>
#include <linux/rculist.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/ndisc.h>

static struct kmem_cache *flow_cache;

static int check_header(struct sk_buff *skb, int len)
{
        if (unlikely(skb->len < len))
                return -EINVAL;
        if (unlikely(!pskb_may_pull(skb, len)))
                return -ENOMEM;
        return 0;
}

static bool arphdr_ok(struct sk_buff *skb)
{
        return pskb_may_pull(skb, skb_network_offset(skb) +
                                  sizeof(struct arp_eth_header));
}

static int check_iphdr(struct sk_buff *skb)
{
        unsigned int nh_ofs = skb_network_offset(skb);
        unsigned int ip_len;
        int err;

        err = check_header(skb, nh_ofs + sizeof(struct iphdr));
        if (unlikely(err))
                return err;

        ip_len = ip_hdrlen(skb);
        if (unlikely(ip_len < sizeof(struct iphdr) ||
                     skb->len < nh_ofs + ip_len))
                return -EINVAL;

        skb_set_transport_header(skb, nh_ofs + ip_len);
        return 0;
}

static bool tcphdr_ok(struct sk_buff *skb)
{
        int th_ofs = skb_transport_offset(skb);
        int tcp_len;

        if (unlikely(!pskb_may_pull(skb, th_ofs + sizeof(struct tcphdr))))
                return false;

        tcp_len = tcp_hdrlen(skb);
        if (unlikely(tcp_len < sizeof(struct tcphdr) ||
                     skb->len < th_ofs + tcp_len))
                return false;

        return true;
}

static bool udphdr_ok(struct sk_buff *skb)
{
        return pskb_may_pull(skb, skb_transport_offset(skb) +
                                  sizeof(struct udphdr));
}

static bool icmphdr_ok(struct sk_buff *skb)
{
        return pskb_may_pull(skb, skb_transport_offset(skb) +
                                  sizeof(struct icmphdr));
}

u64 ovs_flow_used_time(unsigned long flow_jiffies)
{
        struct timespec cur_ts;
        u64 cur_ms, idle_ms;

        ktime_get_ts(&cur_ts);
        idle_ms = jiffies_to_msecs(jiffies - flow_jiffies);
        cur_ms = (u64)cur_ts.tv_sec * MSEC_PER_SEC +
                 cur_ts.tv_nsec / NSEC_PER_MSEC;

        return cur_ms - idle_ms;
}

#define SW_FLOW_KEY_OFFSET(field)               \
        (offsetof(struct sw_flow_key, field) +  \
         FIELD_SIZEOF(struct sw_flow_key, field))

static int parse_ipv6hdr(struct sk_buff *skb, struct sw_flow_key *key,
                         int *key_lenp)
{
        unsigned int nh_ofs = skb_network_offset(skb);
        unsigned int nh_len;
        int payload_ofs;
        struct ipv6hdr *nh;
        uint8_t nexthdr;
        __be16 frag_off;
        int err;

        *key_lenp = SW_FLOW_KEY_OFFSET(ipv6.label);

        err = check_header(skb, nh_ofs + sizeof(*nh));
        if (unlikely(err))
                return err;

        nh = ipv6_hdr(skb);
        nexthdr = nh->nexthdr;
        payload_ofs = (u8 *)(nh + 1) - skb->data;

        key->ip.proto = NEXTHDR_NONE;
        key->ip.tos = ipv6_get_dsfield(nh);
        key->ip.ttl = nh->hop_limit;
        key->ipv6.label = *(__be32 *)nh & htonl(IPV6_FLOWINFO_FLOWLABEL);
        key->ipv6.addr.src = nh->saddr;
        key->ipv6.addr.dst = nh->daddr;

        payload_ofs = ipv6_skip_exthdr(skb, payload_ofs, &nexthdr, &frag_off);
        if (unlikely(payload_ofs < 0))
                return -EINVAL;

        if (frag_off) {
                if (frag_off & htons(~0x7))
                        key->ip.frag = OVS_FRAG_TYPE_LATER;
                else
                        key->ip.frag = OVS_FRAG_TYPE_FIRST;
        }

        nh_len = payload_ofs - nh_ofs;
        skb_set_transport_header(skb, nh_ofs + nh_len);
        key->ip.proto = nexthdr;
        return nh_len;
}

static bool icmp6hdr_ok(struct sk_buff *skb)
{
        return pskb_may_pull(skb, skb_transport_offset(skb) +
                                  sizeof(struct icmp6hdr));
}

#define TCP_FLAGS_OFFSET 13
#define TCP_FLAG_MASK 0x3f

void ovs_flow_used(struct sw_flow *flow, struct sk_buff *skb)
{
        u8 tcp_flags = 0;

        if (flow->key.eth.type == htons(ETH_P_IP) &&
            flow->key.ip.proto == IPPROTO_TCP) {
                u8 *tcp = (u8 *)tcp_hdr(skb);
                tcp_flags = *(tcp + TCP_FLAGS_OFFSET) & TCP_FLAG_MASK;
        }

        spin_lock(&flow->lock);
        flow->used = jiffies;
        flow->packet_count++;
        flow->byte_count += skb->len;
        flow->tcp_flags |= tcp_flags;
        spin_unlock(&flow->lock);
}

struct sw_flow_actions *ovs_flow_actions_alloc(const struct nlattr *actions)
{
        int actions_len = nla_len(actions);
        struct sw_flow_actions *sfa;

        /* At least DP_MAX_PORTS actions are required to be able to flood a
         * packet to every port.  Factor of 2 allows for setting VLAN tags,
         * etc. */
        if (actions_len > 2 * DP_MAX_PORTS * nla_total_size(4))
                return ERR_PTR(-EINVAL);

        sfa = kmalloc(sizeof(*sfa) + actions_len, GFP_KERNEL);
        if (!sfa)
                return ERR_PTR(-ENOMEM);

        sfa->actions_len = actions_len;
        memcpy(sfa->actions, nla_data(actions), actions_len);
        return sfa;
}

struct sw_flow *ovs_flow_alloc(void)
{
        struct sw_flow *flow;

        flow = kmem_cache_alloc(flow_cache, GFP_KERNEL);
        if (!flow)
                return ERR_PTR(-ENOMEM);

        spin_lock_init(&flow->lock);
        flow->sf_acts = NULL;

        return flow;
}

static struct hlist_head *find_bucket(struct flow_table *table, u32 hash)
{
        hash = jhash_1word(hash, table->hash_seed);
        return flex_array_get(table->buckets,
                                (hash & (table->n_buckets - 1)));
}

static struct flex_array *alloc_buckets(unsigned int n_buckets)
{
        struct flex_array *buckets;
        int i, err;

        buckets = flex_array_alloc(sizeof(struct hlist_head *),
                                   n_buckets, GFP_KERNEL);
        if (!buckets)
                return NULL;

        err = flex_array_prealloc(buckets, 0, n_buckets, GFP_KERNEL);
        if (err) {
                flex_array_free(buckets);
                return NULL;
        }

        for (i = 0; i < n_buckets; i++)
                INIT_HLIST_HEAD((struct hlist_head *)
                                        flex_array_get(buckets, i));

        return buckets;
}

static void free_buckets(struct flex_array *buckets)
{
        flex_array_free(buckets);
}

struct flow_table *ovs_flow_tbl_alloc(int new_size)
{
        struct flow_table *table = kmalloc(sizeof(*table), GFP_KERNEL);

        if (!table)
                return NULL;

        table->buckets = alloc_buckets(new_size);

        if (!table->buckets) {
                kfree(table);
                return NULL;
        }
        table->n_buckets = new_size;
        table->count = 0;
        table->node_ver = 0;
        table->keep_flows = false;
        get_random_bytes(&table->hash_seed, sizeof(u32));

        return table;
}

void ovs_flow_tbl_destroy(struct flow_table *table)
{
        int i;

        if (!table)
                return;

        if (table->keep_flows)
                goto skip_flows;

        for (i = 0; i < table->n_buckets; i++) {
                struct sw_flow *flow;
                struct hlist_head *head = flex_array_get(table->buckets, i);
                struct hlist_node *node, *n;
                int ver = table->node_ver;

                hlist_for_each_entry_safe(flow, node, n, head, hash_node[ver]) {
                        hlist_del_rcu(&flow->hash_node[ver]);
                        ovs_flow_free(flow);
                }
        }

skip_flows:
        free_buckets(table->buckets);
        kfree(table);
}

static void flow_tbl_destroy_rcu_cb(struct rcu_head *rcu)
{
        struct flow_table *table = container_of(rcu, struct flow_table, rcu);

        ovs_flow_tbl_destroy(table);
}

void ovs_flow_tbl_deferred_destroy(struct flow_table *table)
{
        if (!table)
                return;

        call_rcu(&table->rcu, flow_tbl_destroy_rcu_cb);
}

struct sw_flow *ovs_flow_tbl_next(struct flow_table *table, u32 *bucket, u32 *last)
{
        struct sw_flow *flow;
        struct hlist_head *head;
        struct hlist_node *n;
        int ver;
        int i;

        ver = table->node_ver;
        while (*bucket < table->n_buckets) {
                i = 0;
                head = flex_array_get(table->buckets, *bucket);
                hlist_for_each_entry_rcu(flow, n, head, hash_node[ver]) {
                        if (i < *last) {
                                i++;
                                continue;
                        }
                        *last = i + 1;
                        return flow;
                }
                (*bucket)++;
                *last = 0;
        }

        return NULL;
}

static void flow_table_copy_flows(struct flow_table *old, struct flow_table *new)
{
        int old_ver;
        int i;

        old_ver = old->node_ver;
        new->node_ver = !old_ver;

        /* Insert in new table. */
        for (i = 0; i < old->n_buckets; i++) {
                struct sw_flow *flow;
                struct hlist_head *head;
                struct hlist_node *n;

                head = flex_array_get(old->buckets, i);

                hlist_for_each_entry(flow, n, head, hash_node[old_ver])
                        ovs_flow_tbl_insert(new, flow);
        }
        old->keep_flows = true;
}

static struct flow_table *__flow_tbl_rehash(struct flow_table *table, int n_buckets)
{
        struct flow_table *new_table;

        new_table = ovs_flow_tbl_alloc(n_buckets);
        if (!new_table)
                return ERR_PTR(-ENOMEM);

        flow_table_copy_flows(table, new_table);

        return new_table;
}

struct flow_table *ovs_flow_tbl_rehash(struct flow_table *table)
{
        return __flow_tbl_rehash(table, table->n_buckets);
}

struct flow_table *ovs_flow_tbl_expand(struct flow_table *table)
{
        return __flow_tbl_rehash(table, table->n_buckets * 2);
}

void ovs_flow_free(struct sw_flow *flow)
{
        if (unlikely(!flow))
                return;

        kfree((struct sf_flow_acts __force *)flow->sf_acts);
        kmem_cache_free(flow_cache, flow);
}

/* RCU callback used by ovs_flow_deferred_free. */
static void rcu_free_flow_callback(struct rcu_head *rcu)
{
        struct sw_flow *flow = container_of(rcu, struct sw_flow, rcu);

        ovs_flow_free(flow);
}

/* Schedules 'flow' to be freed after the next RCU grace period.
 * The caller must hold rcu_read_lock for this to be sensible. */
void ovs_flow_deferred_free(struct sw_flow *flow)
{
        call_rcu(&flow->rcu, rcu_free_flow_callback);
}

/* RCU callback used by ovs_flow_deferred_free_acts. */
static void rcu_free_acts_callback(struct rcu_head *rcu)
{
        struct sw_flow_actions *sf_acts = container_of(rcu,
                        struct sw_flow_actions, rcu);
        kfree(sf_acts);
}

/* Schedules 'sf_acts' to be freed after the next RCU grace period.
 * The caller must hold rcu_read_lock for this to be sensible. */
void ovs_flow_deferred_free_acts(struct sw_flow_actions *sf_acts)
{
        call_rcu(&sf_acts->rcu, rcu_free_acts_callback);
}

static int parse_vlan(struct sk_buff *skb, struct sw_flow_key *key)
{
        struct qtag_prefix {
                __be16 eth_type; /* ETH_P_8021Q */
                __be16 tci;
        };
        struct qtag_prefix *qp;

        if (unlikely(skb->len < sizeof(struct qtag_prefix) + sizeof(__be16)))
                return 0;

        if (unlikely(!pskb_may_pull(skb, sizeof(struct qtag_prefix) +
                                         sizeof(__be16))))
                return -ENOMEM;

        qp = (struct qtag_prefix *) skb->data;
        key->eth.tci = qp->tci | htons(VLAN_TAG_PRESENT);
        __skb_pull(skb, sizeof(struct qtag_prefix));

        return 0;
}

static __be16 parse_ethertype(struct sk_buff *skb)
{
        struct llc_snap_hdr {
                u8  dsap;  /* Always 0xAA */
                u8  ssap;  /* Always 0xAA */
                u8  ctrl;
                u8  oui[3];
                __be16 ethertype;
        };
        struct llc_snap_hdr *llc;
        __be16 proto;

        proto = *(__be16 *) skb->data;
        __skb_pull(skb, sizeof(__be16));

        if (ntohs(proto) >= 1536)
                return proto;

        if (skb->len < sizeof(struct llc_snap_hdr))
                return htons(ETH_P_802_2);

        if (unlikely(!pskb_may_pull(skb, sizeof(struct llc_snap_hdr))))
                return htons(0);

        llc = (struct llc_snap_hdr *) skb->data;
        if (llc->dsap != LLC_SAP_SNAP ||
            llc->ssap != LLC_SAP_SNAP ||
            (llc->oui[0] | llc->oui[1] | llc->oui[2]) != 0)
                return htons(ETH_P_802_2);

        __skb_pull(skb, sizeof(struct llc_snap_hdr));
        return llc->ethertype;
}

static int parse_icmpv6(struct sk_buff *skb, struct sw_flow_key *key,
                        int *key_lenp, int nh_len)
{
        struct icmp6hdr *icmp = icmp6_hdr(skb);
        int error = 0;
        int key_len;

        /* The ICMPv6 type and code fields use the 16-bit transport port
         * fields, so we need to store them in 16-bit network byte order.
         */
        key->ipv6.tp.src = htons(icmp->icmp6_type);
        key->ipv6.tp.dst = htons(icmp->icmp6_code);
        key_len = SW_FLOW_KEY_OFFSET(ipv6.tp);

        if (icmp->icmp6_code == 0 &&
            (icmp->icmp6_type == NDISC_NEIGHBOUR_SOLICITATION ||
             icmp->icmp6_type == NDISC_NEIGHBOUR_ADVERTISEMENT)) {
                int icmp_len = skb->len - skb_transport_offset(skb);
                struct nd_msg *nd;
                int offset;

                key_len = SW_FLOW_KEY_OFFSET(ipv6.nd);

                /* In order to process neighbor discovery options, we need the
                 * entire packet.
                 */
                if (unlikely(icmp_len < sizeof(*nd)))
                        goto out;
                if (unlikely(skb_linearize(skb))) {
                        error = -ENOMEM;
                        goto out;
                }

                nd = (struct nd_msg *)skb_transport_header(skb);
                key->ipv6.nd.target = nd->target;
                key_len = SW_FLOW_KEY_OFFSET(ipv6.nd);

                icmp_len -= sizeof(*nd);
                offset = 0;
                while (icmp_len >= 8) {
                        struct nd_opt_hdr *nd_opt =
                                 (struct nd_opt_hdr *)(nd->opt + offset);
                        int opt_len = nd_opt->nd_opt_len * 8;

                        if (unlikely(!opt_len || opt_len > icmp_len))
                                goto invalid;

                        /* Store the link layer address if the appropriate
                         * option is provided.  It is considered an error if
                         * the same link layer option is specified twice.
                         */
                        if (nd_opt->nd_opt_type == ND_OPT_SOURCE_LL_ADDR
                            && opt_len == 8) {
                                if (unlikely(!is_zero_ether_addr(key->ipv6.nd.sll)))
                                        goto invalid;
                                memcpy(key->ipv6.nd.sll,
                                    &nd->opt[offset+sizeof(*nd_opt)], ETH_ALEN);
                        } else if (nd_opt->nd_opt_type == ND_OPT_TARGET_LL_ADDR
                                   && opt_len == 8) {
                                if (unlikely(!is_zero_ether_addr(key->ipv6.nd.tll)))
                                        goto invalid;
                                memcpy(key->ipv6.nd.tll,
                                    &nd->opt[offset+sizeof(*nd_opt)], ETH_ALEN);
                        }

                        icmp_len -= opt_len;
                        offset += opt_len;
                }
        }

        goto out;

invalid:
        memset(&key->ipv6.nd.target, 0, sizeof(key->ipv6.nd.target));
        memset(key->ipv6.nd.sll, 0, sizeof(key->ipv6.nd.sll));
        memset(key->ipv6.nd.tll, 0, sizeof(key->ipv6.nd.tll));

out:
        *key_lenp = key_len;
        return error;
}

/**
 * ovs_flow_extract - extracts a flow key from an Ethernet frame.
 * @skb: sk_buff that contains the frame, with skb->data pointing to the
 * Ethernet header
 * @in_port: port number on which @skb was received.
 * @key: output flow key
 * @key_lenp: length of output flow key
 *
 * The caller must ensure that skb->len >= ETH_HLEN.
 *
 * Returns 0 if successful, otherwise a negative errno value.
 *
 * Initializes @skb header pointers as follows:
 *
 *    - skb->mac_header: the Ethernet header.
 *
 *    - skb->network_header: just past the Ethernet header, or just past the
 *      VLAN header, to the first byte of the Ethernet payload.
 *
 *    - skb->transport_header: If key->dl_type is ETH_P_IP or ETH_P_IPV6
 *      on output, then just past the IP header, if one is present and
 *      of a correct length, otherwise the same as skb->network_header.
 *      For other key->dl_type values it is left untouched.
 */
int ovs_flow_extract(struct sk_buff *skb, u16 in_port, struct sw_flow_key *key,
                 int *key_lenp)
{
        int error = 0;
        int key_len = SW_FLOW_KEY_OFFSET(eth);
        struct ethhdr *eth;

        memset(key, 0, sizeof(*key));

        key->phy.priority = skb->priority;
        key->phy.in_port = in_port;

        skb_reset_mac_header(skb);

        /* Link layer.  We are guaranteed to have at least the 14 byte Ethernet
         * header in the linear data area.
         */
        eth = eth_hdr(skb);
        memcpy(key->eth.src, eth->h_source, ETH_ALEN);
        memcpy(key->eth.dst, eth->h_dest, ETH_ALEN);

        __skb_pull(skb, 2 * ETH_ALEN);

        if (vlan_tx_tag_present(skb))
                key->eth.tci = htons(skb->vlan_tci);
        else if (eth->h_proto == htons(ETH_P_8021Q))
                if (unlikely(parse_vlan(skb, key)))
                        return -ENOMEM;

        key->eth.type = parse_ethertype(skb);
        if (unlikely(key->eth.type == htons(0)))
                return -ENOMEM;

        skb_reset_network_header(skb);
        __skb_push(skb, skb->data - skb_mac_header(skb));

        /* Network layer. */
        if (key->eth.type == htons(ETH_P_IP)) {
                struct iphdr *nh;
                __be16 offset;

                key_len = SW_FLOW_KEY_OFFSET(ipv4.addr);

                error = check_iphdr(skb);
                if (unlikely(error)) {
                        if (error == -EINVAL) {
                                skb->transport_header = skb->network_header;
                                error = 0;
                        }
                        goto out;
                }

                nh = ip_hdr(skb);
                key->ipv4.addr.src = nh->saddr;
                key->ipv4.addr.dst = nh->daddr;

                key->ip.proto = nh->protocol;
                key->ip.tos = nh->tos;
                key->ip.ttl = nh->ttl;

                offset = nh->frag_off & htons(IP_OFFSET);
                if (offset) {
                        key->ip.frag = OVS_FRAG_TYPE_LATER;
                        goto out;
                }
                if (nh->frag_off & htons(IP_MF) ||
                         skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
                        key->ip.frag = OVS_FRAG_TYPE_FIRST;

                /* Transport layer. */
                if (key->ip.proto == IPPROTO_TCP) {
                        key_len = SW_FLOW_KEY_OFFSET(ipv4.tp);
                        if (tcphdr_ok(skb)) {
                                struct tcphdr *tcp = tcp_hdr(skb);
                                key->ipv4.tp.src = tcp->source;
                                key->ipv4.tp.dst = tcp->dest;
                        }
                } else if (key->ip.proto == IPPROTO_UDP) {
                        key_len = SW_FLOW_KEY_OFFSET(ipv4.tp);
                        if (udphdr_ok(skb)) {
                                struct udphdr *udp = udp_hdr(skb);
                                key->ipv4.tp.src = udp->source;
                                key->ipv4.tp.dst = udp->dest;
                        }
                } else if (key->ip.proto == IPPROTO_ICMP) {
                        key_len = SW_FLOW_KEY_OFFSET(ipv4.tp);
                        if (icmphdr_ok(skb)) {
                                struct icmphdr *icmp = icmp_hdr(skb);
                                /* The ICMP type and code fields use the 16-bit
                                 * transport port fields, so we need to store
                                 * them in 16-bit network byte order. */
                                key->ipv4.tp.src = htons(icmp->type);
                                key->ipv4.tp.dst = htons(icmp->code);
                        }
                }

        } else if (key->eth.type == htons(ETH_P_ARP) && arphdr_ok(skb)) {
                struct arp_eth_header *arp;

                arp = (struct arp_eth_header *)skb_network_header(skb);

                if (arp->ar_hrd == htons(ARPHRD_ETHER)
                                && arp->ar_pro == htons(ETH_P_IP)
                                && arp->ar_hln == ETH_ALEN
                                && arp->ar_pln == 4) {

                        /* We only match on the lower 8 bits of the opcode. */
                        if (ntohs(arp->ar_op) <= 0xff)
                                key->ip.proto = ntohs(arp->ar_op);

                        if (key->ip.proto == ARPOP_REQUEST
                                        || key->ip.proto == ARPOP_REPLY) {
                                memcpy(&key->ipv4.addr.src, arp->ar_sip, sizeof(key->ipv4.addr.src));
                                memcpy(&key->ipv4.addr.dst, arp->ar_tip, sizeof(key->ipv4.addr.dst));
                                memcpy(key->ipv4.arp.sha, arp->ar_sha, ETH_ALEN);
                                memcpy(key->ipv4.arp.tha, arp->ar_tha, ETH_ALEN);
                                key_len = SW_FLOW_KEY_OFFSET(ipv4.arp);
                        }
                }
        } else if (key->eth.type == htons(ETH_P_IPV6)) {
                int nh_len;             /* IPv6 Header + Extensions */

                nh_len = parse_ipv6hdr(skb, key, &key_len);
                if (unlikely(nh_len < 0)) {
                        if (nh_len == -EINVAL)
                                skb->transport_header = skb->network_header;
                        else
                                error = nh_len;
                        goto out;
                }

                if (key->ip.frag == OVS_FRAG_TYPE_LATER)
                        goto out;
                if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
                        key->ip.frag = OVS_FRAG_TYPE_FIRST;

                /* Transport layer. */
                if (key->ip.proto == NEXTHDR_TCP) {
                        key_len = SW_FLOW_KEY_OFFSET(ipv6.tp);
                        if (tcphdr_ok(skb)) {
                                struct tcphdr *tcp = tcp_hdr(skb);
                                key->ipv6.tp.src = tcp->source;
                                key->ipv6.tp.dst = tcp->dest;
                        }
                } else if (key->ip.proto == NEXTHDR_UDP) {
                        key_len = SW_FLOW_KEY_OFFSET(ipv6.tp);
                        if (udphdr_ok(skb)) {
                                struct udphdr *udp = udp_hdr(skb);
                                key->ipv6.tp.src = udp->source;
                                key->ipv6.tp.dst = udp->dest;
                        }
                } else if (key->ip.proto == NEXTHDR_ICMP) {
                        key_len = SW_FLOW_KEY_OFFSET(ipv6.tp);
                        if (icmp6hdr_ok(skb)) {
                                error = parse_icmpv6(skb, key, &key_len, nh_len);
                                if (error < 0)
                                        goto out;
                        }
                }
        }

out:
        *key_lenp = key_len;
        return error;
}

u32 ovs_flow_hash(const struct sw_flow_key *key, int key_len)
{
        return jhash2((u32 *)key, DIV_ROUND_UP(key_len, sizeof(u32)), 0);
}

struct sw_flow *ovs_flow_tbl_lookup(struct flow_table *table,
                                struct sw_flow_key *key, int key_len)
{
        struct sw_flow *flow;
        struct hlist_node *n;
        struct hlist_head *head;
        u32 hash;

        hash = ovs_flow_hash(key, key_len);

        head = find_bucket(table, hash);
        hlist_for_each_entry_rcu(flow, n, head, hash_node[table->node_ver]) {

                if (flow->hash == hash &&
                    !memcmp(&flow->key, key, key_len)) {
                        return flow;
                }
        }
        return NULL;
}

void ovs_flow_tbl_insert(struct flow_table *table, struct sw_flow *flow)
{
        struct hlist_head *head;

        head = find_bucket(table, flow->hash);
        hlist_add_head_rcu(&flow->hash_node[table->node_ver], head);
        table->count++;
}

void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow)
{
        hlist_del_rcu(&flow->hash_node[table->node_ver]);
        table->count--;
        BUG_ON(table->count < 0);
}

/* The size of the argument for each %OVS_KEY_ATTR_* Netlink attribute.  */
const int ovs_key_lens[OVS_KEY_ATTR_MAX + 1] = {
        [OVS_KEY_ATTR_ENCAP] = -1,
        [OVS_KEY_ATTR_PRIORITY] = sizeof(u32),
        [OVS_KEY_ATTR_IN_PORT] = sizeof(u32),
        [OVS_KEY_ATTR_ETHERNET] = sizeof(struct ovs_key_ethernet),
        [OVS_KEY_ATTR_VLAN] = sizeof(__be16),
        [OVS_KEY_ATTR_ETHERTYPE] = sizeof(__be16),
        [OVS_KEY_ATTR_IPV4] = sizeof(struct ovs_key_ipv4),
        [OVS_KEY_ATTR_IPV6] = sizeof(struct ovs_key_ipv6),
        [OVS_KEY_ATTR_TCP] = sizeof(struct ovs_key_tcp),
        [OVS_KEY_ATTR_UDP] = sizeof(struct ovs_key_udp),
        [OVS_KEY_ATTR_ICMP] = sizeof(struct ovs_key_icmp),
        [OVS_KEY_ATTR_ICMPV6] = sizeof(struct ovs_key_icmpv6),
        [OVS_KEY_ATTR_ARP] = sizeof(struct ovs_key_arp),
        [OVS_KEY_ATTR_ND] = sizeof(struct ovs_key_nd),
};

static int ipv4_flow_from_nlattrs(struct sw_flow_key *swkey, int *key_len,
                                  const struct nlattr *a[], u32 *attrs)
{
        const struct ovs_key_icmp *icmp_key;
        const struct ovs_key_tcp *tcp_key;
        const struct ovs_key_udp *udp_key;

        switch (swkey->ip.proto) {
        case IPPROTO_TCP:
                if (!(*attrs & (1 << OVS_KEY_ATTR_TCP)))
                        return -EINVAL;
                *attrs &= ~(1 << OVS_KEY_ATTR_TCP);

                *key_len = SW_FLOW_KEY_OFFSET(ipv4.tp);
                tcp_key = nla_data(a[OVS_KEY_ATTR_TCP]);
                swkey->ipv4.tp.src = tcp_key->tcp_src;
                swkey->ipv4.tp.dst = tcp_key->tcp_dst;
                break;

        case IPPROTO_UDP:
                if (!(*attrs & (1 << OVS_KEY_ATTR_UDP)))
                        return -EINVAL;
                *attrs &= ~(1 << OVS_KEY_ATTR_UDP);

                *key_len = SW_FLOW_KEY_OFFSET(ipv4.tp);
                udp_key = nla_data(a[OVS_KEY_ATTR_UDP]);
                swkey->ipv4.tp.src = udp_key->udp_src;
                swkey->ipv4.tp.dst = udp_key->udp_dst;
                break;

        case IPPROTO_ICMP:
                if (!(*attrs & (1 << OVS_KEY_ATTR_ICMP)))
                        return -EINVAL;
                *attrs &= ~(1 << OVS_KEY_ATTR_ICMP);

                *key_len = SW_FLOW_KEY_OFFSET(ipv4.tp);
                icmp_key = nla_data(a[OVS_KEY_ATTR_ICMP]);
                swkey->ipv4.tp.src = htons(icmp_key->icmp_type);
                swkey->ipv4.tp.dst = htons(icmp_key->icmp_code);
                break;
        }

        return 0;
}

static int ipv6_flow_from_nlattrs(struct sw_flow_key *swkey, int *key_len,
                                  const struct nlattr *a[], u32 *attrs)
{
        const struct ovs_key_icmpv6 *icmpv6_key;
        const struct ovs_key_tcp *tcp_key;
        const struct ovs_key_udp *udp_key;

        switch (swkey->ip.proto) {
        case IPPROTO_TCP:
                if (!(*attrs & (1 << OVS_KEY_ATTR_TCP)))
                        return -EINVAL;
                *attrs &= ~(1 << OVS_KEY_ATTR_TCP);

                *key_len = SW_FLOW_KEY_OFFSET(ipv6.tp);
                tcp_key = nla_data(a[OVS_KEY_ATTR_TCP]);
                swkey->ipv6.tp.src = tcp_key->tcp_src;
                swkey->ipv6.tp.dst = tcp_key->tcp_dst;
                break;

        case IPPROTO_UDP:
                if (!(*attrs & (1 << OVS_KEY_ATTR_UDP)))
                        return -EINVAL;
                *attrs &= ~(1 << OVS_KEY_ATTR_UDP);

                *key_len = SW_FLOW_KEY_OFFSET(ipv6.tp);
                udp_key = nla_data(a[OVS_KEY_ATTR_UDP]);
                swkey->ipv6.tp.src = udp_key->udp_src;
                swkey->ipv6.tp.dst = udp_key->udp_dst;
                break;

        case IPPROTO_ICMPV6:
                if (!(*attrs & (1 << OVS_KEY_ATTR_ICMPV6)))
                        return -EINVAL;
                *attrs &= ~(1 << OVS_KEY_ATTR_ICMPV6);

                *key_len = SW_FLOW_KEY_OFFSET(ipv6.tp);
                icmpv6_key = nla_data(a[OVS_KEY_ATTR_ICMPV6]);
                swkey->ipv6.tp.src = htons(icmpv6_key->icmpv6_type);
                swkey->ipv6.tp.dst = htons(icmpv6_key->icmpv6_code);

                if (swkey->ipv6.tp.src == htons(NDISC_NEIGHBOUR_SOLICITATION) ||
                    swkey->ipv6.tp.src == htons(NDISC_NEIGHBOUR_ADVERTISEMENT)) {
                        const struct ovs_key_nd *nd_key;

                        if (!(*attrs & (1 << OVS_KEY_ATTR_ND)))
                                return -EINVAL;
                        *attrs &= ~(1 << OVS_KEY_ATTR_ND);

                        *key_len = SW_FLOW_KEY_OFFSET(ipv6.nd);
                        nd_key = nla_data(a[OVS_KEY_ATTR_ND]);
                        memcpy(&swkey->ipv6.nd.target, nd_key->nd_target,
                               sizeof(swkey->ipv6.nd.target));
                        memcpy(swkey->ipv6.nd.sll, nd_key->nd_sll, ETH_ALEN);
                        memcpy(swkey->ipv6.nd.tll, nd_key->nd_tll, ETH_ALEN);
                }
                break;
        }

        return 0;
}

static int parse_flow_nlattrs(const struct nlattr *attr,
                              const struct nlattr *a[], u32 *attrsp)
{
        const struct nlattr *nla;
        u32 attrs;
        int rem;

        attrs = 0;
        nla_for_each_nested(nla, attr, rem) {
                u16 type = nla_type(nla);
                int expected_len;

                if (type > OVS_KEY_ATTR_MAX || attrs & (1 << type))
                        return -EINVAL;

                expected_len = ovs_key_lens[type];
                if (nla_len(nla) != expected_len && expected_len != -1)
                        return -EINVAL;

                attrs |= 1 << type;
                a[type] = nla;
        }
        if (rem)
                return -EINVAL;

        *attrsp = attrs;
        return 0;
}

/**
 * ovs_flow_from_nlattrs - parses Netlink attributes into a flow key.
 * @swkey: receives the extracted flow key.
 * @key_lenp: number of bytes used in @swkey.
 * @attr: Netlink attribute holding nested %OVS_KEY_ATTR_* Netlink attribute
 * sequence.
 */
int ovs_flow_from_nlattrs(struct sw_flow_key *swkey, int *key_lenp,
                      const struct nlattr *attr)
{
        const struct nlattr *a[OVS_KEY_ATTR_MAX + 1];
        const struct ovs_key_ethernet *eth_key;
        int key_len;
        u32 attrs;
        int err;

        memset(swkey, 0, sizeof(struct sw_flow_key));
        key_len = SW_FLOW_KEY_OFFSET(eth);

        err = parse_flow_nlattrs(attr, a, &attrs);
        if (err)
                return err;

        /* Metadata attributes. */
        if (attrs & (1 << OVS_KEY_ATTR_PRIORITY)) {
                swkey->phy.priority = nla_get_u32(a[OVS_KEY_ATTR_PRIORITY]);
                attrs &= ~(1 << OVS_KEY_ATTR_PRIORITY);
        }
        if (attrs & (1 << OVS_KEY_ATTR_IN_PORT)) {
                u32 in_port = nla_get_u32(a[OVS_KEY_ATTR_IN_PORT]);
                if (in_port >= DP_MAX_PORTS)
                        return -EINVAL;
                swkey->phy.in_port = in_port;
                attrs &= ~(1 << OVS_KEY_ATTR_IN_PORT);
        } else {

                swkey->phy.in_port = USHRT_MAX;
        }

        /* Data attributes. */
        if (!(attrs & (1 << OVS_KEY_ATTR_ETHERNET)))
                return -EINVAL;
        attrs &= ~(1 << OVS_KEY_ATTR_ETHERNET);

        eth_key = nla_data(a[OVS_KEY_ATTR_ETHERNET]);
        memcpy(swkey->eth.src, eth_key->eth_src, ETH_ALEN);
        memcpy(swkey->eth.dst, eth_key->eth_dst, ETH_ALEN);

        if (attrs & (1u << OVS_KEY_ATTR_ETHERTYPE) &&
            nla_get_be16(a[OVS_KEY_ATTR_ETHERTYPE]) == htons(ETH_P_8021Q)) {
                const struct nlattr *encap;
                __be16 tci;

                if (attrs != ((1 << OVS_KEY_ATTR_VLAN) |
                              (1 << OVS_KEY_ATTR_ETHERTYPE) |
                              (1 << OVS_KEY_ATTR_ENCAP)))
                        return -EINVAL;

                encap = a[OVS_KEY_ATTR_ENCAP];
                tci = nla_get_be16(a[OVS_KEY_ATTR_VLAN]);
                if (tci & htons(VLAN_TAG_PRESENT)) {
                        swkey->eth.tci = tci;

                        err = parse_flow_nlattrs(encap, a, &attrs);
                        if (err)
                                return err;
                } else if (!tci) {
                        /* Corner case for truncated 802.1Q header. */
                        if (nla_len(encap))
                                return -EINVAL;

                        swkey->eth.type = htons(ETH_P_8021Q);
                        *key_lenp = key_len;
                        return 0;
                } else {
                        return -EINVAL;
                }
        }

        if (attrs & (1 << OVS_KEY_ATTR_ETHERTYPE)) {
                swkey->eth.type = nla_get_be16(a[OVS_KEY_ATTR_ETHERTYPE]);
                if (ntohs(swkey->eth.type) < 1536)
                        return -EINVAL;
                attrs &= ~(1 << OVS_KEY_ATTR_ETHERTYPE);
        } else {
                swkey->eth.type = htons(ETH_P_802_2);
        }

        if (swkey->eth.type == htons(ETH_P_IP)) {
                const struct ovs_key_ipv4 *ipv4_key;

                if (!(attrs & (1 << OVS_KEY_ATTR_IPV4)))
                        return -EINVAL;
                attrs &= ~(1 << OVS_KEY_ATTR_IPV4);

                key_len = SW_FLOW_KEY_OFFSET(ipv4.addr);
                ipv4_key = nla_data(a[OVS_KEY_ATTR_IPV4]);
                if (ipv4_key->ipv4_frag > OVS_FRAG_TYPE_MAX)
                        return -EINVAL;
                swkey->ip.proto = ipv4_key->ipv4_proto;
                swkey->ip.tos = ipv4_key->ipv4_tos;
                swkey->ip.ttl = ipv4_key->ipv4_ttl;
                swkey->ip.frag = ipv4_key->ipv4_frag;
                swkey->ipv4.addr.src = ipv4_key->ipv4_src;
                swkey->ipv4.addr.dst = ipv4_key->ipv4_dst;

                if (swkey->ip.frag != OVS_FRAG_TYPE_LATER) {
                        err = ipv4_flow_from_nlattrs(swkey, &key_len, a, &attrs);
                        if (err)
                                return err;
                }
        } else if (swkey->eth.type == htons(ETH_P_IPV6)) {
                const struct ovs_key_ipv6 *ipv6_key;

                if (!(attrs & (1 << OVS_KEY_ATTR_IPV6)))
                        return -EINVAL;
                attrs &= ~(1 << OVS_KEY_ATTR_IPV6);

                key_len = SW_FLOW_KEY_OFFSET(ipv6.label);
                ipv6_key = nla_data(a[OVS_KEY_ATTR_IPV6]);
                if (ipv6_key->ipv6_frag > OVS_FRAG_TYPE_MAX)
                        return -EINVAL;
                swkey->ipv6.label = ipv6_key->ipv6_label;
                swkey->ip.proto = ipv6_key->ipv6_proto;
                swkey->ip.tos = ipv6_key->ipv6_tclass;
                swkey->ip.ttl = ipv6_key->ipv6_hlimit;
                swkey->ip.frag = ipv6_key->ipv6_frag;
                memcpy(&swkey->ipv6.addr.src, ipv6_key->ipv6_src,
                       sizeof(swkey->ipv6.addr.src));
                memcpy(&swkey->ipv6.addr.dst, ipv6_key->ipv6_dst,
                       sizeof(swkey->ipv6.addr.dst));

                if (swkey->ip.frag != OVS_FRAG_TYPE_LATER) {
                        err = ipv6_flow_from_nlattrs(swkey, &key_len, a, &attrs);
                        if (err)
                                return err;
                }
        } else if (swkey->eth.type == htons(ETH_P_ARP)) {
                const struct ovs_key_arp *arp_key;

                if (!(attrs & (1 << OVS_KEY_ATTR_ARP)))
                        return -EINVAL;
                attrs &= ~(1 << OVS_KEY_ATTR_ARP);

                key_len = SW_FLOW_KEY_OFFSET(ipv4.arp);
                arp_key = nla_data(a[OVS_KEY_ATTR_ARP]);
                swkey->ipv4.addr.src = arp_key->arp_sip;
                swkey->ipv4.addr.dst = arp_key->arp_tip;
                if (arp_key->arp_op & htons(0xff00))
                        return -EINVAL;
                swkey->ip.proto = ntohs(arp_key->arp_op);
                memcpy(swkey->ipv4.arp.sha, arp_key->arp_sha, ETH_ALEN);
                memcpy(swkey->ipv4.arp.tha, arp_key->arp_tha, ETH_ALEN);
        }

        if (attrs)
                return -EINVAL;
        *key_lenp = key_len;

        return 0;
}

/**
 * ovs_flow_metadata_from_nlattrs - parses Netlink attributes into a flow key.
 * @in_port: receives the extracted input port.
 * @key: Netlink attribute holding nested %OVS_KEY_ATTR_* Netlink attribute
 * sequence.
 *
 * This parses a series of Netlink attributes that form a flow key, which must
 * take the same form accepted by flow_from_nlattrs(), but only enough of it to
 * get the metadata, that is, the parts of the flow key that cannot be
 * extracted from the packet itself.
 */
int ovs_flow_metadata_from_nlattrs(u32 *priority, u16 *in_port,
                               const struct nlattr *attr)
{
        const struct nlattr *nla;
        int rem;

        *in_port = USHRT_MAX;
        *priority = 0;

        nla_for_each_nested(nla, attr, rem) {
                int type = nla_type(nla);

                if (type <= OVS_KEY_ATTR_MAX && ovs_key_lens[type] > 0) {
                        if (nla_len(nla) != ovs_key_lens[type])
                                return -EINVAL;

                        switch (type) {
                        case OVS_KEY_ATTR_PRIORITY:
                                *priority = nla_get_u32(nla);
                                break;

                        case OVS_KEY_ATTR_IN_PORT:
                                if (nla_get_u32(nla) >= DP_MAX_PORTS)
                                        return -EINVAL;
                                *in_port = nla_get_u32(nla);
                                break;
                        }
                }
        }
        if (rem)
                return -EINVAL;
        return 0;
}

int ovs_flow_to_nlattrs(const struct sw_flow_key *swkey, struct sk_buff *skb)
{
        struct ovs_key_ethernet *eth_key;
        struct nlattr *nla, *encap;

        if (swkey->phy.priority)
                NLA_PUT_U32(skb, OVS_KEY_ATTR_PRIORITY, swkey->phy.priority);

        if (swkey->phy.in_port != USHRT_MAX)
                NLA_PUT_U32(skb, OVS_KEY_ATTR_IN_PORT, swkey->phy.in_port);

        nla = nla_reserve(skb, OVS_KEY_ATTR_ETHERNET, sizeof(*eth_key));
        if (!nla)
                goto nla_put_failure;
        eth_key = nla_data(nla);
        memcpy(eth_key->eth_src, swkey->eth.src, ETH_ALEN);
        memcpy(eth_key->eth_dst, swkey->eth.dst, ETH_ALEN);

        if (swkey->eth.tci || swkey->eth.type == htons(ETH_P_8021Q)) {
                NLA_PUT_BE16(skb, OVS_KEY_ATTR_ETHERTYPE, htons(ETH_P_8021Q));
                NLA_PUT_BE16(skb, OVS_KEY_ATTR_VLAN, swkey->eth.tci);
                encap = nla_nest_start(skb, OVS_KEY_ATTR_ENCAP);
                if (!swkey->eth.tci)
                        goto unencap;
        } else {
                encap = NULL;
        }

        if (swkey->eth.type == htons(ETH_P_802_2))
                goto unencap;

        NLA_PUT_BE16(skb, OVS_KEY_ATTR_ETHERTYPE, swkey->eth.type);

        if (swkey->eth.type == htons(ETH_P_IP)) {
                struct ovs_key_ipv4 *ipv4_key;

                nla = nla_reserve(skb, OVS_KEY_ATTR_IPV4, sizeof(*ipv4_key));
                if (!nla)
                        goto nla_put_failure;
                ipv4_key = nla_data(nla);
                ipv4_key->ipv4_src = swkey->ipv4.addr.src;
                ipv4_key->ipv4_dst = swkey->ipv4.addr.dst;
                ipv4_key->ipv4_proto = swkey->ip.proto;
                ipv4_key->ipv4_tos = swkey->ip.tos;
                ipv4_key->ipv4_ttl = swkey->ip.ttl;
                ipv4_key->ipv4_frag = swkey->ip.frag;
        } else if (swkey->eth.type == htons(ETH_P_IPV6)) {
                struct ovs_key_ipv6 *ipv6_key;

                nla = nla_reserve(skb, OVS_KEY_ATTR_IPV6, sizeof(*ipv6_key));
                if (!nla)
                        goto nla_put_failure;
                ipv6_key = nla_data(nla);
                memcpy(ipv6_key->ipv6_src, &swkey->ipv6.addr.src,
                                sizeof(ipv6_key->ipv6_src));
                memcpy(ipv6_key->ipv6_dst, &swkey->ipv6.addr.dst,
                                sizeof(ipv6_key->ipv6_dst));
                ipv6_key->ipv6_label = swkey->ipv6.label;
                ipv6_key->ipv6_proto = swkey->ip.proto;
                ipv6_key->ipv6_tclass = swkey->ip.tos;
                ipv6_key->ipv6_hlimit = swkey->ip.ttl;
                ipv6_key->ipv6_frag = swkey->ip.frag;
        } else if (swkey->eth.type == htons(ETH_P_ARP)) {
                struct ovs_key_arp *arp_key;

                nla = nla_reserve(skb, OVS_KEY_ATTR_ARP, sizeof(*arp_key));
                if (!nla)
                        goto nla_put_failure;
                arp_key = nla_data(nla);
                memset(arp_key, 0, sizeof(struct ovs_key_arp));
                arp_key->arp_sip = swkey->ipv4.addr.src;
                arp_key->arp_tip = swkey->ipv4.addr.dst;
                arp_key->arp_op = htons(swkey->ip.proto);
                memcpy(arp_key->arp_sha, swkey->ipv4.arp.sha, ETH_ALEN);
                memcpy(arp_key->arp_tha, swkey->ipv4.arp.tha, ETH_ALEN);
        }

        if ((swkey->eth.type == htons(ETH_P_IP) ||
             swkey->eth.type == htons(ETH_P_IPV6)) &&
             swkey->ip.frag != OVS_FRAG_TYPE_LATER) {

                if (swkey->ip.proto == IPPROTO_TCP) {
                        struct ovs_key_tcp *tcp_key;

                        nla = nla_reserve(skb, OVS_KEY_ATTR_TCP, sizeof(*tcp_key));
                        if (!nla)
                                goto nla_put_failure;
                        tcp_key = nla_data(nla);
                        if (swkey->eth.type == htons(ETH_P_IP)) {
                                tcp_key->tcp_src = swkey->ipv4.tp.src;
                                tcp_key->tcp_dst = swkey->ipv4.tp.dst;
                        } else if (swkey->eth.type == htons(ETH_P_IPV6)) {
                                tcp_key->tcp_src = swkey->ipv6.tp.src;
                                tcp_key->tcp_dst = swkey->ipv6.tp.dst;
                        }
                } else if (swkey->ip.proto == IPPROTO_UDP) {
                        struct ovs_key_udp *udp_key;

                        nla = nla_reserve(skb, OVS_KEY_ATTR_UDP, sizeof(*udp_key));
                        if (!nla)
                                goto nla_put_failure;
                        udp_key = nla_data(nla);
                        if (swkey->eth.type == htons(ETH_P_IP)) {
                                udp_key->udp_src = swkey->ipv4.tp.src;
                                udp_key->udp_dst = swkey->ipv4.tp.dst;
                        } else if (swkey->eth.type == htons(ETH_P_IPV6)) {
                                udp_key->udp_src = swkey->ipv6.tp.src;
                                udp_key->udp_dst = swkey->ipv6.tp.dst;
                        }
                } else if (swkey->eth.type == htons(ETH_P_IP) &&
                           swkey->ip.proto == IPPROTO_ICMP) {
                        struct ovs_key_icmp *icmp_key;

                        nla = nla_reserve(skb, OVS_KEY_ATTR_ICMP, sizeof(*icmp_key));
                        if (!nla)
                                goto nla_put_failure;
                        icmp_key = nla_data(nla);
                        icmp_key->icmp_type = ntohs(swkey->ipv4.tp.src);
                        icmp_key->icmp_code = ntohs(swkey->ipv4.tp.dst);
                } else if (swkey->eth.type == htons(ETH_P_IPV6) &&
                           swkey->ip.proto == IPPROTO_ICMPV6) {
                        struct ovs_key_icmpv6 *icmpv6_key;

                        nla = nla_reserve(skb, OVS_KEY_ATTR_ICMPV6,
                                                sizeof(*icmpv6_key));
                        if (!nla)
                                goto nla_put_failure;
                        icmpv6_key = nla_data(nla);
                        icmpv6_key->icmpv6_type = ntohs(swkey->ipv6.tp.src);
                        icmpv6_key->icmpv6_code = ntohs(swkey->ipv6.tp.dst);

                        if (icmpv6_key->icmpv6_type == NDISC_NEIGHBOUR_SOLICITATION ||
                            icmpv6_key->icmpv6_type == NDISC_NEIGHBOUR_ADVERTISEMENT) {
                                struct ovs_key_nd *nd_key;

                                nla = nla_reserve(skb, OVS_KEY_ATTR_ND, sizeof(*nd_key));
                                if (!nla)
                                        goto nla_put_failure;
                                nd_key = nla_data(nla);
                                memcpy(nd_key->nd_target, &swkey->ipv6.nd.target,
                                                        sizeof(nd_key->nd_target));
                                memcpy(nd_key->nd_sll, swkey->ipv6.nd.sll, ETH_ALEN);
                                memcpy(nd_key->nd_tll, swkey->ipv6.nd.tll, ETH_ALEN);
                        }
                }
        }

unencap:
        if (encap)
                nla_nest_end(skb, encap);

        return 0;

nla_put_failure:
        return -EMSGSIZE;
}

/* Initializes the flow module.
 * Returns zero if successful or a negative error code. */
int ovs_flow_init(void)
{
        flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow), 0,
                                        0, NULL);
        if (flow_cache == NULL)
                return -ENOMEM;

        return 0;
}

/* Uninitializes the flow module. */
void ovs_flow_exit(void)
{
        kmem_cache_destroy(flow_cache);
}