/*
 * INET        An implementation of the TCP/IP protocol suite for the LINUX
 *             operating system.  INET is implemented using the  BSD Socket
 *             interface as the means of communication with the user level.
 *
 *             Support for INET6 connection oriented protocols.
 *
 * Authors:    See the TCPv6 sources
 *
 *             This program is free software; you can redistribute it and/or
 *             modify it under the terms of the GNU General Public License
 *             as published by the Free Software Foundation; either version
 *             2 of the License, or(at your option) any later version.
 */

#include <linux/module.h>
#include <linux/in6.h>
#include <linux/ipv6.h>
#include <linux/jhash.h>
#include <linux/slab.h>

#include <net/addrconf.h>
#include <net/inet_connection_sock.h>
#include <net/inet_ecn.h>
#include <net/inet_hashtables.h>
#include <net/ip6_route.h>
#include <net/sock.h>
#include <net/inet6_connection_sock.h>

int inet6_csk_bind_conflict(const struct sock *sk,
                            const struct inet_bind_bucket *tb)
{
        const struct sock *sk2;
        const struct hlist_node *node;

        /* We must walk the whole port owner list in this case. -DaveM */
        /*
         * See comment in inet_csk_bind_conflict about sock lookup
         * vs net namespaces issues.
         */
        sk_for_each_bound(sk2, node, &tb->owners) {
                if (sk != sk2 &&
                    (!sk->sk_bound_dev_if ||
                     !sk2->sk_bound_dev_if ||
                     sk->sk_bound_dev_if == sk2->sk_bound_dev_if) &&
                    (!sk->sk_reuse || !sk2->sk_reuse ||
                     sk2->sk_state == TCP_LISTEN) &&
                     ipv6_rcv_saddr_equal(sk, sk2))
                        break;
        }

        return node != NULL;
}

EXPORT_SYMBOL_GPL(inet6_csk_bind_conflict);

struct dst_entry *inet6_csk_route_req(struct sock *sk,
                                      const struct request_sock *req)
{
        struct inet6_request_sock *treq = inet6_rsk(req);
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct in6_addr *final_p, final;
        struct dst_entry *dst;
        struct flowi6 fl6;

        memset(&fl6, 0, sizeof(fl6));
        fl6.flowi6_proto = IPPROTO_TCP;
        fl6.daddr = treq->rmt_addr;
        final_p = fl6_update_dst(&fl6, np->opt, &final);
        fl6.saddr = treq->loc_addr;
        fl6.flowi6_oif = sk->sk_bound_dev_if;
        fl6.flowi6_mark = sk->sk_mark;
        fl6.fl6_dport = inet_rsk(req)->rmt_port;
        fl6.fl6_sport = inet_rsk(req)->loc_port;
        security_req_classify_flow(req, flowi6_to_flowi(&fl6));

        dst = ip6_dst_lookup_flow(sk, &fl6, final_p, false);
        if (IS_ERR(dst))
                return NULL;

        return dst;
}

/*
 * request_sock (formerly open request) hash tables.
 */
static u32 inet6_synq_hash(const struct in6_addr *raddr, const __be16 rport,
                           const u32 rnd, const u32 synq_hsize)
{
        u32 c;

        c = jhash_3words((__force u32)raddr->s6_addr32[0],
                         (__force u32)raddr->s6_addr32[1],
                         (__force u32)raddr->s6_addr32[2],
                         rnd);

        c = jhash_2words((__force u32)raddr->s6_addr32[3],
                         (__force u32)rport,
                         c);

        return c & (synq_hsize - 1);
}

struct request_sock *inet6_csk_search_req(const struct sock *sk,
                                          struct request_sock ***prevp,
                                          const __be16 rport,
                                          const struct in6_addr *raddr,
                                          const struct in6_addr *laddr,
                                          const int iif)
{
        const struct inet_connection_sock *icsk = inet_csk(sk);
        struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
        struct request_sock *req, **prev;

        for (prev = &lopt->syn_table[inet6_synq_hash(raddr, rport,
                                                     lopt->hash_rnd,
                                                     lopt->nr_table_entries)];
             (req = *prev) != NULL;
             prev = &req->dl_next) {
                const struct inet6_request_sock *treq = inet6_rsk(req);

                if (inet_rsk(req)->rmt_port == rport &&
                    req->rsk_ops->family == AF_INET6 &&
                    ipv6_addr_equal(&treq->rmt_addr, raddr) &&
                    ipv6_addr_equal(&treq->loc_addr, laddr) &&
                    (!treq->iif || treq->iif == iif)) {
                        WARN_ON(req->sk != NULL);
                        *prevp = prev;
                        return req;
                }
        }

        return NULL;
}

EXPORT_SYMBOL_GPL(inet6_csk_search_req);

void inet6_csk_reqsk_queue_hash_add(struct sock *sk,
                                    struct request_sock *req,
                                    const unsigned long timeout)
{
        struct inet_connection_sock *icsk = inet_csk(sk);
        struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
        const u32 h = inet6_synq_hash(&inet6_rsk(req)->rmt_addr,
                                      inet_rsk(req)->rmt_port,
                                      lopt->hash_rnd, lopt->nr_table_entries);

        reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
        inet_csk_reqsk_queue_added(sk, timeout);
}

EXPORT_SYMBOL_GPL(inet6_csk_reqsk_queue_hash_add);

void inet6_csk_addr2sockaddr(struct sock *sk, struct sockaddr * uaddr)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) uaddr;

        sin6->sin6_family = AF_INET6;
        sin6->sin6_addr = np->daddr;
        sin6->sin6_port = inet_sk(sk)->inet_dport;
        /* We do not store received flowlabel for TCP */
        sin6->sin6_flowinfo = 0;
        sin6->sin6_scope_id = 0;
        if (sk->sk_bound_dev_if &&
            ipv6_addr_type(&sin6->sin6_addr) & IPV6_ADDR_LINKLOCAL)
                sin6->sin6_scope_id = sk->sk_bound_dev_if;
}

EXPORT_SYMBOL_GPL(inet6_csk_addr2sockaddr);

static inline
void __inet6_csk_dst_store(struct sock *sk, struct dst_entry *dst,
                           struct in6_addr *daddr, struct in6_addr *saddr)
{
        __ip6_dst_store(sk, dst, daddr, saddr);

#ifdef CONFIG_XFRM
        {
                struct rt6_info *rt = (struct rt6_info  *)dst;
                rt->rt6i_flow_cache_genid = atomic_read(&flow_cache_genid);
        }
#endif
}

static inline
struct dst_entry *__inet6_csk_dst_check(struct sock *sk, u32 cookie)
{
        struct dst_entry *dst;

        dst = __sk_dst_check(sk, cookie);

#ifdef CONFIG_XFRM
        if (dst) {
                struct rt6_info *rt = (struct rt6_info *)dst;
                if (rt->rt6i_flow_cache_genid != atomic_read(&flow_cache_genid)) {
                        __sk_dst_reset(sk);
                        dst = NULL;
                }
        }
#endif

        return dst;
}

int inet6_csk_xmit(struct sk_buff *skb, struct flowi *fl_unused)
{
        struct sock *sk = skb->sk;
        struct inet_sock *inet = inet_sk(sk);
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct flowi6 fl6;
        struct dst_entry *dst;
        struct in6_addr *final_p, final;
        int res;

        memset(&fl6, 0, sizeof(fl6));
        fl6.flowi6_proto = sk->sk_protocol;
        fl6.daddr = np->daddr;
        fl6.saddr = np->saddr;
        fl6.flowlabel = np->flow_label;
        IP6_ECN_flow_xmit(sk, fl6.flowlabel);
        fl6.flowi6_oif = sk->sk_bound_dev_if;
        fl6.flowi6_mark = sk->sk_mark;
        fl6.fl6_sport = inet->inet_sport;
        fl6.fl6_dport = inet->inet_dport;
        security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));

        final_p = fl6_update_dst(&fl6, np->opt, &final);

        dst = __inet6_csk_dst_check(sk, np->dst_cookie);

        if (dst == NULL) {
                dst = ip6_dst_lookup_flow(sk, &fl6, final_p, false);

                if (IS_ERR(dst)) {
                        sk->sk_err_soft = -PTR_ERR(dst);
                        sk->sk_route_caps = 0;
                        kfree_skb(skb);
                        return PTR_ERR(dst);
                }

                __inet6_csk_dst_store(sk, dst, NULL, NULL);
        }

        rcu_read_lock();
        skb_dst_set_noref(skb, dst);

        /* Restore final destination back after routing done */
        fl6.daddr = np->daddr;

        res = ip6_xmit(sk, skb, &fl6, np->opt, np->tclass);
        rcu_read_unlock();
        return res;
}
EXPORT_SYMBOL_GPL(inet6_csk_xmit);