text: /*
   * Copyright (c) 2007-2011 Nicira, Inc.
   *
   * 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.eth.type == htons(ETH_P_IPV6)) &&
  	    flow->key.ip.proto == IPPROTO_TCP &&
  	    likely(skb->len >= skb_transport_offset(skb) + sizeof(struct tcphdr))) {
  		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))
  		goto nla_put_failure;
  
  	if (swkey->phy.in_port != USHRT_MAX &&
  	    nla_put_u32(skb, OVS_KEY_ATTR_IN_PORT, swkey->phy.in_port))
  		goto nla_put_failure;
  
  	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)) {
  		if (nla_put_be16(skb, OVS_KEY_ATTR_ETHERTYPE, htons(ETH_P_8021Q)) ||
  		    nla_put_be16(skb, OVS_KEY_ATTR_VLAN, swkey->eth.tci))
  			goto nla_put_failure;
  		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;
  
  	if (nla_put_be16(skb, OVS_KEY_ATTR_ETHERTYPE, swkey->eth.type))
  		goto nla_put_failure;
  
  	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);
  }
  