/*
 * 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>
#include <net/sock_reuseport.h>

int inet6_csk_bind_conflict(const struct sock *sk,
                            const struct inet_bind_bucket *tb, bool relax)
{
        const struct sock *sk2;
        int reuse = sk->sk_reuse;
        int reuseport = sk->sk_reuseport;
        kuid_t uid = sock_i_uid((struct sock *)sk);

        /* 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, &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)) {
                        if ((!reuse || !sk2->sk_reuse ||
                             sk2->sk_state == TCP_LISTEN) &&
                            (!reuseport || !sk2->sk_reuseport ||
                             rcu_access_pointer(sk->sk_reuseport_cb) ||
                             (sk2->sk_state != TCP_TIME_WAIT &&
                              !uid_eq(uid,
                                      sock_i_uid((struct sock *)sk2))))) {
                                if (ipv6_rcv_saddr_equal(sk, sk2, true))
                                        break;
                        }
                        if (!relax && reuse && sk2->sk_reuse &&
                            sk2->sk_state != TCP_LISTEN &&
                            ipv6_rcv_saddr_equal(sk, sk2, true))
                                break;
                }
        }

        return sk2 != NULL;
}
EXPORT_SYMBOL_GPL(inet6_csk_bind_conflict);

struct dst_entry *inet6_csk_route_req(const struct sock *sk,
                                      struct flowi6 *fl6,
                                      const struct request_sock *req,
                                      u8 proto)
{
        struct inet_request_sock *ireq = inet_rsk(req);
        const struct ipv6_pinfo *np = inet6_sk(sk);
        struct in6_addr *final_p, final;
        struct dst_entry *dst;

        memset(fl6, 0, sizeof(*fl6));
        fl6->flowi6_proto = proto;
        fl6->daddr = ireq->ir_v6_rmt_addr;
        rcu_read_lock();
        final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);
        rcu_read_unlock();
        fl6->saddr = ireq->ir_v6_loc_addr;
        fl6->flowi6_oif = ireq->ir_iif;
        fl6->flowi6_mark = ireq->ir_mark;
        fl6->fl6_dport = ireq->ir_rmt_port;
        fl6->fl6_sport = htons(ireq->ir_num);
        security_req_classify_flow(req, flowi6_to_flowi(fl6));

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

        return dst;
}
EXPORT_SYMBOL(inet6_csk_route_req);

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

        sin6->sin6_family = AF_INET6;
        sin6->sin6_addr = sk->sk_v6_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 = ipv6_iface_scope_id(&sin6->sin6_addr,
                                                  sk->sk_bound_dev_if);
}
EXPORT_SYMBOL_GPL(inet6_csk_addr2sockaddr);

static inline
struct dst_entry *__inet6_csk_dst_check(struct sock *sk, u32 cookie)
{
        return __sk_dst_check(sk, cookie);
}

static struct dst_entry *inet6_csk_route_socket(struct sock *sk,
                                                struct flowi6 *fl6)
{
        struct inet_sock *inet = inet_sk(sk);
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct in6_addr *final_p, final;
        struct dst_entry *dst;

        memset(fl6, 0, sizeof(*fl6));
        fl6->flowi6_proto = sk->sk_protocol;
        fl6->daddr = sk->sk_v6_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));

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

        dst = __inet6_csk_dst_check(sk, np->dst_cookie);
        if (!dst) {
                dst = ip6_dst_lookup_flow(sk, fl6, final_p);

                if (!IS_ERR(dst))
                        ip6_dst_store(sk, dst, NULL, NULL);
        }
        return dst;
}

int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl_unused)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct flowi6 fl6;
        struct dst_entry *dst;
        int res;

        dst = inet6_csk_route_socket(sk, &fl6);
        if (IS_ERR(dst)) {
                sk->sk_err_soft = -PTR_ERR(dst);
                sk->sk_route_caps = 0;
                kfree_skb(skb);
                return PTR_ERR(dst);
        }

        rcu_read_lock();
        skb_dst_set_noref(skb, dst);

        /* Restore final destination back after routing done */
        fl6.daddr = sk->sk_v6_daddr;

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

struct dst_entry *inet6_csk_update_pmtu(struct sock *sk, u32 mtu)
{
        struct flowi6 fl6;
        struct dst_entry *dst = inet6_csk_route_socket(sk, &fl6);

        if (IS_ERR(dst))
                return NULL;
        dst->ops->update_pmtu(dst, sk, NULL, mtu);

        dst = inet6_csk_route_socket(sk, &fl6);
        return IS_ERR(dst) ? NULL : dst;
}
EXPORT_SYMBOL_GPL(inet6_csk_update_pmtu);