#include <linux/skbuff.h>

  #include <linux/export.h>

  #include <linux/ip.h>
  #include <linux/ipv6.h>
  #include <linux/if_vlan.h>
  #include <net/ip.h>

  #include <net/ipv6.h>

  #include <linux/igmp.h>
  #include <linux/icmp.h>
  #include <linux/sctp.h>
  #include <linux/dccp.h>

  #include <linux/if_tunnel.h>
  #include <linux/if_pppox.h>
  #include <linux/ppp_defs.h>
  #include <net/flow_keys.h>

  /* copy saddr & daddr, possibly using 64bit load/store
   * Equivalent to :	flow->src = iph->saddr;
   *			flow->dst = iph->daddr;
   */
  static void iph_to_flow_copy_addrs(struct flow_keys *flow, const struct iphdr *iph)
  {
  	BUILD_BUG_ON(offsetof(typeof(*flow), dst) !=
  		     offsetof(typeof(*flow), src) + sizeof(flow->src));
  	memcpy(&flow->src, &iph->saddr, sizeof(flow->src) + sizeof(flow->dst));
  }

  /**
   * skb_flow_get_ports - extract the upper layer ports and return them
   * @skb: buffer to extract the ports from
   * @thoff: transport header offset
   * @ip_proto: protocol for which to get port offset
   *
   * The function will try to retrieve the ports at offset thoff + poff where poff
   * is the protocol port offset returned from proto_ports_offset
   */
  __be32 skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto)
  {
  	int poff = proto_ports_offset(ip_proto);
  
  	if (poff >= 0) {
  		__be32 *ports, _ports;
  
  		ports = skb_header_pointer(skb, thoff + poff,
  					   sizeof(_ports), &_ports);
  		if (ports)
  			return *ports;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL(skb_flow_get_ports);

  bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow)
  {

  	int nhoff = skb_network_offset(skb);

  	u8 ip_proto;
  	__be16 proto = skb->protocol;
  
  	memset(flow, 0, sizeof(*flow));
  
  again:
  	switch (proto) {

  	case htons(ETH_P_IP): {

  		const struct iphdr *iph;
  		struct iphdr _iph;
  ip:
  		iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);

  		if (!iph || iph->ihl < 5)

  			return false;

  		nhoff += iph->ihl * 4;

  		ip_proto = iph->protocol;

  		if (ip_is_fragment(iph))
  			ip_proto = 0;

  		iph_to_flow_copy_addrs(flow, iph);

  		break;
  	}

  	case htons(ETH_P_IPV6): {

  		const struct ipv6hdr *iph;
  		struct ipv6hdr _iph;
  ipv6:
  		iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
  		if (!iph)
  			return false;
  
  		ip_proto = iph->nexthdr;

  		flow->src = (__force __be32)ipv6_addr_hash(&iph->saddr);
  		flow->dst = (__force __be32)ipv6_addr_hash(&iph->daddr);

  		nhoff += sizeof(struct ipv6hdr);
  		break;
  	}

  	case htons(ETH_P_8021AD):
  	case htons(ETH_P_8021Q): {

  		const struct vlan_hdr *vlan;
  		struct vlan_hdr _vlan;
  
  		vlan = skb_header_pointer(skb, nhoff, sizeof(_vlan), &_vlan);
  		if (!vlan)
  			return false;
  
  		proto = vlan->h_vlan_encapsulated_proto;
  		nhoff += sizeof(*vlan);
  		goto again;
  	}

  	case htons(ETH_P_PPP_SES): {

  		struct {
  			struct pppoe_hdr hdr;
  			__be16 proto;
  		} *hdr, _hdr;
  		hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
  		if (!hdr)
  			return false;
  		proto = hdr->proto;
  		nhoff += PPPOE_SES_HLEN;
  		switch (proto) {

  		case htons(PPP_IP):

  			goto ip;

  		case htons(PPP_IPV6):

  			goto ipv6;
  		default:
  			return false;
  		}
  	}
  	default:
  		return false;
  	}
  
  	switch (ip_proto) {
  	case IPPROTO_GRE: {
  		struct gre_hdr {
  			__be16 flags;
  			__be16 proto;
  		} *hdr, _hdr;
  
  		hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
  		if (!hdr)
  			return false;
  		/*
  		 * Only look inside GRE if version zero and no
  		 * routing
  		 */
  		if (!(hdr->flags & (GRE_VERSION|GRE_ROUTING))) {
  			proto = hdr->proto;
  			nhoff += 4;
  			if (hdr->flags & GRE_CSUM)
  				nhoff += 4;
  			if (hdr->flags & GRE_KEY)
  				nhoff += 4;
  			if (hdr->flags & GRE_SEQ)
  				nhoff += 4;

  			if (proto == htons(ETH_P_TEB)) {
  				const struct ethhdr *eth;
  				struct ethhdr _eth;
  
  				eth = skb_header_pointer(skb, nhoff,
  							 sizeof(_eth), &_eth);
  				if (!eth)
  					return false;
  				proto = eth->h_proto;
  				nhoff += sizeof(*eth);
  			}

  			goto again;
  		}
  		break;
  	}
  	case IPPROTO_IPIP:

  		proto = htons(ETH_P_IP);
  		goto ip;

  	case IPPROTO_IPV6:
  		proto = htons(ETH_P_IPV6);
  		goto ipv6;

  	default:
  		break;
  	}
  
  	flow->ip_proto = ip_proto;

  	flow->ports = skb_flow_get_ports(skb, nhoff, ip_proto);

  	flow->thoff = (u16) nhoff;

  	return true;
  }
  EXPORT_SYMBOL(skb_flow_dissect);

  
  static u32 hashrnd __read_mostly;

  static __always_inline void __flow_hash_secret_init(void)
  {
  	net_get_random_once(&hashrnd, sizeof(hashrnd));
  }
  
  static __always_inline u32 __flow_hash_3words(u32 a, u32 b, u32 c)
  {
  	__flow_hash_secret_init();
  	return jhash_3words(a, b, c, hashrnd);
  }
  
  static __always_inline u32 __flow_hash_1word(u32 a)
  {
  	__flow_hash_secret_init();
  	return jhash_1word(a, hashrnd);
  }

  
  /*

   * __skb_get_hash: calculate a flow hash based on src/dst addresses

   * and src/dst port numbers.  Sets hash in skb to non-zero hash value
   * on success, zero indicates no valid hash.  Also, sets l4_hash in skb

   * if hash is a canonical 4-tuple hash over transport ports.
   */

  void __skb_get_hash(struct sk_buff *skb)

  {
  	struct flow_keys keys;
  	u32 hash;
  
  	if (!skb_flow_dissect(skb, &keys))
  		return;
  
  	if (keys.ports)

  		skb->l4_hash = 1;

  
  	/* get a consistent hash (same value on both flow directions) */
  	if (((__force u32)keys.dst < (__force u32)keys.src) ||
  	    (((__force u32)keys.dst == (__force u32)keys.src) &&
  	     ((__force u16)keys.port16[1] < (__force u16)keys.port16[0]))) {
  		swap(keys.dst, keys.src);
  		swap(keys.port16[0], keys.port16[1]);
  	}

  	hash = __flow_hash_3words((__force u32)keys.dst,
  				  (__force u32)keys.src,
  				  (__force u32)keys.ports);

  	if (!hash)
  		hash = 1;

  	skb->hash = hash;

  }

  EXPORT_SYMBOL(__skb_get_hash);

  
  /*
   * Returns a Tx hash based on the given packet descriptor a Tx queues' number
   * to be used as a distribution range.
   */
  u16 __skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb,
  		  unsigned int num_tx_queues)
  {
  	u32 hash;
  	u16 qoffset = 0;
  	u16 qcount = num_tx_queues;
  
  	if (skb_rx_queue_recorded(skb)) {
  		hash = skb_get_rx_queue(skb);
  		while (unlikely(hash >= num_tx_queues))
  			hash -= num_tx_queues;
  		return hash;
  	}
  
  	if (dev->num_tc) {
  		u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
  		qoffset = dev->tc_to_txq[tc].offset;
  		qcount = dev->tc_to_txq[tc].count;
  	}
  
  	if (skb->sk && skb->sk->sk_hash)
  		hash = skb->sk->sk_hash;
  	else
  		hash = (__force u16) skb->protocol;

  	hash = __flow_hash_1word(hash);

  
  	return (u16) (((u64) hash * qcount) >> 32) + qoffset;
  }
  EXPORT_SYMBOL(__skb_tx_hash);

  /* __skb_get_poff() returns the offset to the payload as far as it could
   * be dissected. The main user is currently BPF, so that we can dynamically
   * truncate packets without needing to push actual payload to the user
   * space and can analyze headers only, instead.
   */
  u32 __skb_get_poff(const struct sk_buff *skb)
  {
  	struct flow_keys keys;
  	u32 poff = 0;
  
  	if (!skb_flow_dissect(skb, &keys))
  		return 0;
  
  	poff += keys.thoff;
  	switch (keys.ip_proto) {
  	case IPPROTO_TCP: {
  		const struct tcphdr *tcph;
  		struct tcphdr _tcph;
  
  		tcph = skb_header_pointer(skb, poff, sizeof(_tcph), &_tcph);
  		if (!tcph)
  			return poff;
  
  		poff += max_t(u32, sizeof(struct tcphdr), tcph->doff * 4);
  		break;
  	}
  	case IPPROTO_UDP:
  	case IPPROTO_UDPLITE:
  		poff += sizeof(struct udphdr);
  		break;
  	/* For the rest, we do not really care about header
  	 * extensions at this point for now.
  	 */
  	case IPPROTO_ICMP:
  		poff += sizeof(struct icmphdr);
  		break;
  	case IPPROTO_ICMPV6:
  		poff += sizeof(struct icmp6hdr);
  		break;
  	case IPPROTO_IGMP:
  		poff += sizeof(struct igmphdr);
  		break;
  	case IPPROTO_DCCP:
  		poff += sizeof(struct dccp_hdr);
  		break;
  	case IPPROTO_SCTP:
  		poff += sizeof(struct sctphdr);
  		break;
  	}
  
  	return poff;
  }

  static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
  {
  #ifdef CONFIG_XPS
  	struct xps_dev_maps *dev_maps;
  	struct xps_map *map;
  	int queue_index = -1;
  
  	rcu_read_lock();
  	dev_maps = rcu_dereference(dev->xps_maps);
  	if (dev_maps) {
  		map = rcu_dereference(
  		    dev_maps->cpu_map[raw_smp_processor_id()]);
  		if (map) {
  			if (map->len == 1)
  				queue_index = map->queues[0];
  			else {
  				u32 hash;
  				if (skb->sk && skb->sk->sk_hash)
  					hash = skb->sk->sk_hash;
  				else
  					hash = (__force u16) skb->protocol ^

  					    skb->hash;

  				hash = __flow_hash_1word(hash);

  				queue_index = map->queues[
  				    ((u64)hash * map->len) >> 32];
  			}
  			if (unlikely(queue_index >= dev->real_num_tx_queues))
  				queue_index = -1;
  		}
  	}
  	rcu_read_unlock();
  
  	return queue_index;
  #else
  	return -1;
  #endif
  }

  static u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)

  {
  	struct sock *sk = skb->sk;
  	int queue_index = sk_tx_queue_get(sk);
  
  	if (queue_index < 0 || skb->ooo_okay ||
  	    queue_index >= dev->real_num_tx_queues) {
  		int new_index = get_xps_queue(dev, skb);
  		if (new_index < 0)
  			new_index = skb_tx_hash(dev, skb);

  		if (queue_index != new_index && sk &&
  		    rcu_access_pointer(sk->sk_dst_cache))

  			sk_tx_queue_set(sk, new_index);

  
  		queue_index = new_index;
  	}
  
  	return queue_index;
  }

  
  struct netdev_queue *netdev_pick_tx(struct net_device *dev,

  				    struct sk_buff *skb,
  				    void *accel_priv)

  {
  	int queue_index = 0;
  
  	if (dev->real_num_tx_queues != 1) {
  		const struct net_device_ops *ops = dev->netdev_ops;
  		if (ops->ndo_select_queue)

  			queue_index = ops->ndo_select_queue(dev, skb, accel_priv,
  							    __netdev_pick_tx);

  		else
  			queue_index = __netdev_pick_tx(dev, skb);

  
  		if (!accel_priv)

  			queue_index = netdev_cap_txqueue(dev, queue_index);

  	}
  
  	skb_set_queue_mapping(skb, queue_index);
  	return netdev_get_tx_queue(dev, queue_index);
  }