#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>
#include <scsi/fc/fc_fcoe.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: sk_buff to extract the ports from
 * @thoff: transport header offset
 * @ip_proto: protocol for which to get port offset
 * @data: raw buffer pointer to the packet, if NULL use skb->data
 * @hlen: packet header length, if @data is NULL use skb_headlen(skb)
 *
 * 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,
                            void *data, int hlen)
{
        int poff = proto_ports_offset(ip_proto);

        if (!data) {
                data = skb->data;
                hlen = skb_headlen(skb);
        }

        if (poff >= 0) {
                __be32 *ports, _ports;

                ports = __skb_header_pointer(skb, thoff + poff,
                                             sizeof(_ports), data, hlen, &_ports);
                if (ports)
                        return *ports;
        }

        return 0;
}
EXPORT_SYMBOL(__skb_flow_get_ports);

/**
 * __skb_flow_dissect - extract the flow_keys struct and return it
 * @skb: sk_buff to extract the flow from, can be NULL if the rest are specified
 * @data: raw buffer pointer to the packet, if NULL use skb->data
 * @proto: protocol for which to get the flow, if @data is NULL use skb->protocol
 * @nhoff: network header offset, if @data is NULL use skb_network_offset(skb)
 * @hlen: packet header length, if @data is NULL use skb_headlen(skb)
 *
 * The function will try to retrieve the struct flow_keys from either the skbuff
 * or a raw buffer specified by the rest parameters
 */
bool __skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow,
                        void *data, __be16 proto, int nhoff, int hlen)
{
        u8 ip_proto;

        if (!data) {
                data = skb->data;
                proto = skb->protocol;
                nhoff = skb_network_offset(skb);
                hlen = skb_headlen(skb);
        }

        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), data, hlen, &_iph);
                if (!iph || iph->ihl < 5)
                        return false;
                nhoff += iph->ihl * 4;

                ip_proto = iph->protocol;
                if (ip_is_fragment(iph))
                        ip_proto = 0;

                /* skip the address processing if skb is NULL.  The assumption
                 * here is that if there is no skb we are not looking for flow
                 * info but lengths and protocols.
                 */
                if (!skb)
                        break;

                iph_to_flow_copy_addrs(flow, iph);
                break;
        }
        case htons(ETH_P_IPV6): {
                const struct ipv6hdr *iph;
                struct ipv6hdr _iph;
                __be32 flow_label;

ipv6:
                iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
                if (!iph)
                        return false;

                ip_proto = iph->nexthdr;
                nhoff += sizeof(struct ipv6hdr);

                /* see comment above in IPv4 section */
                if (!skb)
                        break;

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

                flow_label = ip6_flowlabel(iph);
                if (flow_label) {
                        /* Awesome, IPv6 packet has a flow label so we can
                         * use that to represent the ports without any
                         * further dissection.
                         */
                        flow->n_proto = proto;
                        flow->ip_proto = ip_proto;
                        flow->ports = flow_label;
                        flow->thoff = (u16)nhoff;

                        return true;
                }

                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), data, hlen, &_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), data, hlen, &_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;
                }
        }
        case htons(ETH_P_TIPC): {
                struct {
                        __be32 pre[3];
                        __be32 srcnode;
                } *hdr, _hdr;
                hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
                if (!hdr)
                        return false;
                flow->src = hdr->srcnode;
                flow->dst = 0;
                flow->n_proto = proto;
                flow->thoff = (u16)nhoff;
                return true;
        }
        case htons(ETH_P_FCOE):
                flow->thoff = (u16)(nhoff + FCOE_HEADER_LEN);
                /* fall through */
        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), data, hlen, &_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),
                                                           data, hlen, &_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->n_proto = proto;
        flow->ip_proto = ip_proto;
        flow->thoff = (u16) nhoff;

        /* unless skb is set we don't need to record port info */
        if (skb)
                flow->ports = __skb_flow_get_ports(skb, nhoff, ip_proto,
                                                   data, hlen);

        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 inline u32 __flow_hash_from_keys(struct flow_keys *keys)
{
        u32 hash;

        /* 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;

        return hash;
}

u32 flow_hash_from_keys(struct flow_keys *keys)
{
        return __flow_hash_from_keys(keys);
}
EXPORT_SYMBOL(flow_hash_from_keys);

/*
 * __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;

        if (!skb_flow_dissect(skb, &keys))
                return;

        if (keys.ports)
                skb->l4_hash = 1;

        skb->sw_hash = 1;

        skb->hash = __flow_hash_from_keys(&keys);
}
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, 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;
        }

        return (u16) reciprocal_scale(skb_get_hash(skb), qcount) + qoffset;
}
EXPORT_SYMBOL(__skb_tx_hash);

u32 __skb_get_poff(const struct sk_buff *skb, void *data,
                   const struct flow_keys *keys, int hlen)
{
        u32 poff = keys->thoff;

        switch (keys->ip_proto) {
        case IPPROTO_TCP: {
                /* access doff as u8 to avoid unaligned access */
                const u8 *doff;
                u8 _doff;

                doff = __skb_header_pointer(skb, poff + 12, sizeof(_doff),
                                            data, hlen, &_doff);
                if (!doff)
                        return poff;

                poff += max_t(u32, sizeof(struct tcphdr), (*doff & 0xF0) >> 2);
                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;
}

/* 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;

        if (!skb_flow_dissect(skb, &keys))
                return 0;

        return __skb_get_poff(skb, skb->data, &keys, skb_headlen(skb));
}

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[skb->sender_cpu - 1]);
                if (map) {
                        if (map->len == 1)
                                queue_index = map->queues[0];
                        else
                                queue_index = map->queues[reciprocal_scale(skb_get_hash(skb),
                                                                           map->len)];
                        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;

#ifdef CONFIG_XPS
        if (skb->sender_cpu == 0)
                skb->sender_cpu = raw_smp_processor_id() + 1;
#endif

        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);
}