/*
 * Copyright (c) 2007-2013 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/sctp.h>
#include <linux/smp.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/ip_tunnels.h>
#include <net/ipv6.h>
#include <net/ndisc.h>

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 TCP_FLAGS_BE16(tp) (*(__be16 *)&tcp_flag_word(tp) & htons(0x0FFF))

void ovs_flow_stats_update(struct sw_flow *flow, __be16 tcp_flags,
                           struct sk_buff *skb)
{
        struct flow_stats *stats;
        int node = numa_node_id();

        stats = rcu_dereference(flow->stats[node]);

        /* Check if already have node-specific stats. */
        if (likely(stats)) {
                spin_lock(&stats->lock);
                /* Mark if we write on the pre-allocated stats. */
                if (node == 0 && unlikely(flow->stats_last_writer != node))
                        flow->stats_last_writer = node;
        } else {
                stats = rcu_dereference(flow->stats[0]); /* Pre-allocated. */
                spin_lock(&stats->lock);

                /* If the current NUMA-node is the only writer on the
                 * pre-allocated stats keep using them.
                 */
                if (unlikely(flow->stats_last_writer != node)) {
                        /* A previous locker may have already allocated the
                         * stats, so we need to check again.  If node-specific
                         * stats were already allocated, we update the pre-
                         * allocated stats as we have already locked them.
                         */
                        if (likely(flow->stats_last_writer != NUMA_NO_NODE)
                            && likely(!rcu_dereference(flow->stats[node]))) {
                                /* Try to allocate node-specific stats. */
                                struct flow_stats *new_stats;

                                new_stats =
                                        kmem_cache_alloc_node(flow_stats_cache,
                                                              GFP_THISNODE |
                                                              __GFP_NOMEMALLOC,
                                                              node);
                                if (likely(new_stats)) {
                                        new_stats->used = jiffies;
                                        new_stats->packet_count = 1;
                                        new_stats->byte_count = skb->len;
                                        new_stats->tcp_flags = tcp_flags;
                                        spin_lock_init(&new_stats->lock);

                                        rcu_assign_pointer(flow->stats[node],
                                                           new_stats);
                                        goto unlock;
                                }
                        }
                        flow->stats_last_writer = node;
                }
        }

        stats->used = jiffies;
        stats->packet_count++;
        stats->byte_count += skb->len;
        stats->tcp_flags |= tcp_flags;
unlock:
        spin_unlock(&stats->lock);
}

/* Must be called with rcu_read_lock or ovs_mutex. */
void ovs_flow_stats_get(const struct sw_flow *flow,
                        struct ovs_flow_stats *ovs_stats,
                        unsigned long *used, __be16 *tcp_flags)
{
        int node;

        *used = 0;
        *tcp_flags = 0;
        memset(ovs_stats, 0, sizeof(*ovs_stats));

        for_each_node(node) {
                struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[node]);

                if (stats) {
                        /* Local CPU may write on non-local stats, so we must
                         * block bottom-halves here.
                         */
                        spin_lock_bh(&stats->lock);
                        if (!*used || time_after(stats->used, *used))
                                *used = stats->used;
                        *tcp_flags |= stats->tcp_flags;
                        ovs_stats->n_packets += stats->packet_count;
                        ovs_stats->n_bytes += stats->byte_count;
                        spin_unlock_bh(&stats->lock);
                }
        }
}

/* Called with ovs_mutex. */
void ovs_flow_stats_clear(struct sw_flow *flow)
{
        int node;

        for_each_node(node) {
                struct flow_stats *stats = ovsl_dereference(flow->stats[node]);

                if (stats) {
                        spin_lock_bh(&stats->lock);
                        stats->used = 0;
                        stats->packet_count = 0;
                        stats->byte_count = 0;
                        stats->tcp_flags = 0;
                        spin_unlock_bh(&stats->lock);
                }
        }
}

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 sctphdr_ok(struct sk_buff *skb)
{
        return pskb_may_pull(skb, skb_transport_offset(skb) +
                                  sizeof(struct sctphdr));
}

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

static int parse_ipv6hdr(struct sk_buff *skb, struct sw_flow_key *key)
{
        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;

        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));
}

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) >= ETH_P_802_3_MIN)
                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));

        if (ntohs(llc->ethertype) >= ETH_P_802_3_MIN)
                return llc->ethertype;

        return htons(ETH_P_802_2);
}

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

        /* 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->tp.src = htons(icmp->icmp6_type);
        key->tp.dst = htons(icmp->icmp6_code);

        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;

                /* In order to process neighbor discovery options, we need the
                 * entire packet.
                 */
                if (unlikely(icmp_len < sizeof(*nd)))
                        return 0;

                if (unlikely(skb_linearize(skb)))
                        return -ENOMEM;

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

                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))
                                return 0;

                        /* 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;
                                ether_addr_copy(key->ipv6.nd.sll,
                                                &nd->opt[offset+sizeof(*nd_opt)]);
                        } 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;
                                ether_addr_copy(key->ipv6.nd.tll,
                                                &nd->opt[offset+sizeof(*nd_opt)]);
                        }

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

        return 0;

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));

        return 0;
}

/**
 * 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
 *
 * 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->eth.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->eth.type values it is left untouched.
 */
int ovs_flow_extract(struct sk_buff *skb, u16 in_port, struct sw_flow_key *key)
{
        int error;
        struct ethhdr *eth;

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

        key->phy.priority = skb->priority;
        if (OVS_CB(skb)->tun_key)
                memcpy(&key->tun_key, OVS_CB(skb)->tun_key, sizeof(key->tun_key));
        key->phy.in_port = in_port;
        key->phy.skb_mark = skb->mark;

        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);
        ether_addr_copy(key->eth.src, eth->h_source);
        ether_addr_copy(key->eth.dst, eth->h_dest);

        __skb_pull(skb, 2 * ETH_ALEN);
        /* We are going to push all headers that we pull, so no need to
         * update skb->csum here.
         */

        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;

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

                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;
                        return 0;
                }
                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) {
                        if (tcphdr_ok(skb)) {
                                struct tcphdr *tcp = tcp_hdr(skb);
                                key->tp.src = tcp->source;
                                key->tp.dst = tcp->dest;
                                key->tp.flags = TCP_FLAGS_BE16(tcp);
                        }
                } else if (key->ip.proto == IPPROTO_UDP) {
                        if (udphdr_ok(skb)) {
                                struct udphdr *udp = udp_hdr(skb);
                                key->tp.src = udp->source;
                                key->tp.dst = udp->dest;
                        }
                } else if (key->ip.proto == IPPROTO_SCTP) {
                        if (sctphdr_ok(skb)) {
                                struct sctphdr *sctp = sctp_hdr(skb);
                                key->tp.src = sctp->source;
                                key->tp.dst = sctp->dest;
                        }
                } else if (key->ip.proto == IPPROTO_ICMP) {
                        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->tp.src = htons(icmp->type);
                                key->tp.dst = htons(icmp->code);
                        }
                }

        } else if ((key->eth.type == htons(ETH_P_ARP) ||
                   key->eth.type == htons(ETH_P_RARP)) && 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);
                        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));
                        ether_addr_copy(key->ipv4.arp.sha, arp->ar_sha);
                        ether_addr_copy(key->ipv4.arp.tha, arp->ar_tha);
                }
        } else if (key->eth.type == htons(ETH_P_IPV6)) {
                int nh_len;             /* IPv6 Header + Extensions */

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

                if (key->ip.frag == OVS_FRAG_TYPE_LATER)
                        return 0;
                if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
                        key->ip.frag = OVS_FRAG_TYPE_FIRST;

                /* Transport layer. */
                if (key->ip.proto == NEXTHDR_TCP) {
                        if (tcphdr_ok(skb)) {
                                struct tcphdr *tcp = tcp_hdr(skb);
                                key->tp.src = tcp->source;
                                key->tp.dst = tcp->dest;
                                key->tp.flags = TCP_FLAGS_BE16(tcp);
                        }
                } else if (key->ip.proto == NEXTHDR_UDP) {
                        if (udphdr_ok(skb)) {
                                struct udphdr *udp = udp_hdr(skb);
                                key->tp.src = udp->source;
                                key->tp.dst = udp->dest;
                        }
                } else if (key->ip.proto == NEXTHDR_SCTP) {
                        if (sctphdr_ok(skb)) {
                                struct sctphdr *sctp = sctp_hdr(skb);
                                key->tp.src = sctp->source;
                                key->tp.dst = sctp->dest;
                        }
                } else if (key->ip.proto == NEXTHDR_ICMP) {
                        if (icmp6hdr_ok(skb)) {
                                error = parse_icmpv6(skb, key, nh_len);
                                if (error)
                                        return error;
                        }
                }
        }

        return 0;
}