/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * NET          Generic infrastructure for INET connection oriented protocols.
 *
 *              Definitions for inet_connection_sock 
 *
 * Authors:     Many people, see the TCP sources
 *
 *              From code originally in TCP
 */
#ifndef _INET_CONNECTION_SOCK_H
#define _INET_CONNECTION_SOCK_H

#include <linux/compiler.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/poll.h>
#include <linux/kernel.h>
#include <linux/sockptr.h>

#include <net/inet_sock.h>
#include <net/request_sock.h>

/* Cancel timers, when they are not required. */
#undef INET_CSK_CLEAR_TIMERS

struct inet_bind_bucket;
struct inet_bind2_bucket;
struct tcp_congestion_ops;

/*
 * Pointers to address related TCP functions
 * (i.e. things that depend on the address family)
 */
struct inet_connection_sock_af_ops {
        int         (*queue_xmit)(struct sock *sk, struct sk_buff *skb, struct flowi *fl);
        void        (*send_check)(struct sock *sk, struct sk_buff *skb);
        int         (*rebuild_header)(struct sock *sk);
        void        (*sk_rx_dst_set)(struct sock *sk, const struct sk_buff *skb);
        int         (*conn_request)(struct sock *sk, struct sk_buff *skb);
        struct sock *(*syn_recv_sock)(const struct sock *sk, struct sk_buff *skb,
                                      struct request_sock *req,
                                      struct dst_entry *dst,
                                      struct request_sock *req_unhash,
                                      bool *own_req,
                                      void (*opt_child_init)(struct sock *newsk,
                                                             const struct sock *sk));
        u16         net_header_len;
        int         (*setsockopt)(struct sock *sk, int level, int optname,
                                  sockptr_t optval, unsigned int optlen);
        int         (*getsockopt)(struct sock *sk, int level, int optname,
                                  char __user *optval, int __user *optlen);
        void        (*mtu_reduced)(struct sock *sk);
};

/** inet_connection_sock - INET connection oriented sock
 *
 * @icsk_accept_queue:     FIFO of established children
 * @icsk_bind_hash:        Bind node
 * @icsk_bind2_hash:       Bind node in the bhash2 table
 * @icsk_delack_timer:     Delayed ACK timer
 * @icsk_keepalive_timer:  Keepalive timer
 * @mptcp_tout_timer: mptcp timer
 * @icsk_rto:              Retransmit timeout
 * @icsk_pmtu_cookie       Last pmtu seen by socket
 * @icsk_ca_ops            Pluggable congestion control hook
 * @icsk_af_ops            Operations which are AF_INET{4,6} specific
 * @icsk_ulp_ops           Pluggable ULP control hook
 * @icsk_ulp_data          ULP private data
 * @icsk_ca_state:         Congestion control state
 * @icsk_retransmits:      Number of unrecovered [RTO] timeouts
 * @icsk_pending:          Scheduled timer event
 * @icsk_backoff:          Backoff
 * @icsk_syn_retries:      Number of allowed SYN (or equivalent) retries
 * @icsk_probes_out:       unanswered 0 window probes
 * @icsk_ext_hdr_len:      Network protocol overhead (IP/IPv6 options)
 * @icsk_ack:              Delayed ACK control data
 * @icsk_mtup;             MTU probing control data
 * @icsk_probes_tstamp:    Probe timestamp (cleared by non-zero window ack)
 * @icsk_user_timeout:     TCP_USER_TIMEOUT value
 */
struct inet_connection_sock {
        /* inet_sock has to be the first member! */
        struct inet_sock          icsk_inet;
        struct request_sock_queue icsk_accept_queue;
        struct inet_bind_bucket   *icsk_bind_hash;
        struct inet_bind2_bucket  *icsk_bind2_hash;
        struct timer_list         icsk_delack_timer;
        union {
                struct timer_list icsk_keepalive_timer;
                struct timer_list mptcp_tout_timer;
        };
        __u32                     icsk_rto;
        __u32                     icsk_rto_min;
        u32                       icsk_rto_max;
        __u32                     icsk_delack_max;
        __u32                     icsk_pmtu_cookie;
        const struct tcp_congestion_ops *icsk_ca_ops;
        const struct inet_connection_sock_af_ops *icsk_af_ops;
        const struct tcp_ulp_ops  *icsk_ulp_ops;
        void __rcu                *icsk_ulp_data;
        unsigned int              (*icsk_sync_mss)(struct sock *sk, u32 pmtu);
        __u8                      icsk_ca_state:5,
                                  icsk_ca_initialized:1,
                                  icsk_ca_setsockopt:1,
                                  icsk_ca_dst_locked:1;
        __u8                      icsk_retransmits;
        __u8                      icsk_pending;
        __u8                      icsk_backoff;
        __u8                      icsk_syn_retries;
        __u8                      icsk_probes_out;
        __u16                     icsk_ext_hdr_len;
        struct {
                __u8              pending;       /* ACK is pending                         */
                __u8              quick;         /* Scheduled number of quick acks         */
                __u8              pingpong;      /* The session is interactive             */
                __u8              retry;         /* Number of attempts                     */
                #define ATO_BITS 8
                __u32             ato:ATO_BITS,  /* Predicted tick of soft clock           */
                                  lrcv_flowlabel:20, /* last received ipv6 flowlabel       */
                                  dst_quick_ack:1, /* cache dst RTAX_QUICKACK              */
                                  unused:3;
                __u32             lrcvtime;      /* timestamp of last received data packet */
                __u16             last_seg_size; /* Size of last incoming segment          */
                __u16             rcv_mss;       /* MSS used for delayed ACK decisions     */
        } icsk_ack;
        struct {
                /* Range of MTUs to search */
                int               search_high;
                int               search_low;

                /* Information on the current probe. */
                u32               probe_size:31,
                /* Is the MTUP feature enabled for this connection? */
                                  enabled:1;

                u32               probe_timestamp;
        } icsk_mtup;
        u32                       icsk_probes_tstamp;
        u32                       icsk_user_timeout;

        u64                       icsk_ca_priv[104 / sizeof(u64)];
#define ICSK_CA_PRIV_SIZE         sizeof_field(struct inet_connection_sock, icsk_ca_priv)
};

#define ICSK_TIME_RETRANS       1       /* Retransmit timer */
#define ICSK_TIME_DACK          2       /* Delayed ack timer */
#define ICSK_TIME_PROBE0        3       /* Zero window probe timer */
#define ICSK_TIME_LOSS_PROBE    5       /* Tail loss probe timer */
#define ICSK_TIME_REO_TIMEOUT   6       /* Reordering timer */

#define inet_csk(ptr) container_of_const(ptr, struct inet_connection_sock, icsk_inet.sk)

static inline void *inet_csk_ca(const struct sock *sk)
{
        return (void *)inet_csk(sk)->icsk_ca_priv;
}

struct sock *inet_csk_clone_lock(const struct sock *sk,
                                 const struct request_sock *req,
                                 const gfp_t priority);

enum inet_csk_ack_state_t {
        ICSK_ACK_SCHED  = 1,
        ICSK_ACK_TIMER  = 2,
        ICSK_ACK_PUSHED = 4,
        ICSK_ACK_PUSHED2 = 8,
        ICSK_ACK_NOW = 16,      /* Send the next ACK immediately (once) */
        ICSK_ACK_NOMEM = 32,
};

void inet_csk_init_xmit_timers(struct sock *sk,
                               void (*retransmit_handler)(struct timer_list *),
                               void (*delack_handler)(struct timer_list *),
                               void (*keepalive_handler)(struct timer_list *));
void inet_csk_clear_xmit_timers(struct sock *sk);
void inet_csk_clear_xmit_timers_sync(struct sock *sk);

static inline void inet_csk_schedule_ack(struct sock *sk)
{
        inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_SCHED;
}

static inline int inet_csk_ack_scheduled(const struct sock *sk)
{
        return inet_csk(sk)->icsk_ack.pending & ICSK_ACK_SCHED;
}

static inline void inet_csk_delack_init(struct sock *sk)
{
        memset(&inet_csk(sk)->icsk_ack, 0, sizeof(inet_csk(sk)->icsk_ack));
}

static inline unsigned long tcp_timeout_expires(const struct sock *sk)
{
        return READ_ONCE(sk->tcp_retransmit_timer.expires);
}

static inline unsigned long
icsk_delack_timeout(const struct inet_connection_sock *icsk)
{
        return READ_ONCE(icsk->icsk_delack_timer.expires);
}

static inline void inet_csk_clear_xmit_timer(struct sock *sk, const int what)
{
        struct inet_connection_sock *icsk = inet_csk(sk);

        if (what == ICSK_TIME_RETRANS || what == ICSK_TIME_PROBE0) {
                smp_store_release(&icsk->icsk_pending, 0);
#ifdef INET_CSK_CLEAR_TIMERS
                sk_stop_timer(sk, &sk->tcp_retransmit_timer);
#endif
        } else if (what == ICSK_TIME_DACK) {
                smp_store_release(&icsk->icsk_ack.pending, 0);
                icsk->icsk_ack.retry = 0;
#ifdef INET_CSK_CLEAR_TIMERS
                sk_stop_timer(sk, &icsk->icsk_delack_timer);
#endif
        } else {
                pr_debug("inet_csk BUG: unknown timer value\n");
        }
}

/*
 *      Reset the retransmission timer
 */
static inline void inet_csk_reset_xmit_timer(struct sock *sk, const int what,
                                             unsigned long when,
                                             const unsigned long max_when)
{
        struct inet_connection_sock *icsk = inet_csk(sk);

        if (when > max_when) {
                pr_debug("reset_xmit_timer: sk=%p %d when=0x%lx, caller=%p\n",
                         sk, what, when, (void *)_THIS_IP_);
                when = max_when;
        }

        when += jiffies;
        if (what == ICSK_TIME_RETRANS || what == ICSK_TIME_PROBE0 ||
            what == ICSK_TIME_LOSS_PROBE || what == ICSK_TIME_REO_TIMEOUT) {
                smp_store_release(&icsk->icsk_pending, what);
                sk_reset_timer(sk, &sk->tcp_retransmit_timer, when);
        } else if (what == ICSK_TIME_DACK) {
                smp_store_release(&icsk->icsk_ack.pending,
                                  icsk->icsk_ack.pending | ICSK_ACK_TIMER);
                sk_reset_timer(sk, &icsk->icsk_delack_timer, when);
        } else {
                pr_debug("inet_csk BUG: unknown timer value\n");
        }
}

static inline unsigned long
inet_csk_rto_backoff(const struct inet_connection_sock *icsk,
                     unsigned long max_when)
{
        u64 when = (u64)icsk->icsk_rto << icsk->icsk_backoff;

        return (unsigned long)min_t(u64, when, max_when);
}

struct sock *inet_csk_accept(struct sock *sk, struct proto_accept_arg *arg);

int inet_csk_get_port(struct sock *sk, unsigned short snum);

struct dst_entry *inet_csk_route_req(const struct sock *sk, struct flowi4 *fl4,
                                     const struct request_sock *req);
struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
                                            struct sock *newsk,
                                            const struct request_sock *req);

struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
                                      struct request_sock *req,
                                      struct sock *child);
bool inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req);
struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
                                         struct request_sock *req,
                                         bool own_req);

static inline void inet_csk_reqsk_queue_added(struct sock *sk)
{
        reqsk_queue_added(&inet_csk(sk)->icsk_accept_queue);
}

static inline int inet_csk_reqsk_queue_len(const struct sock *sk)
{
        return reqsk_queue_len(&inet_csk(sk)->icsk_accept_queue);
}

static inline int inet_csk_reqsk_queue_is_full(const struct sock *sk)
{
        return inet_csk_reqsk_queue_len(sk) > READ_ONCE(sk->sk_max_ack_backlog);
}

bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req);
void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req);

void inet_csk_destroy_sock(struct sock *sk);
void inet_csk_prepare_for_destroy_sock(struct sock *sk);
void inet_csk_prepare_forced_close(struct sock *sk);

/*
 * LISTEN is a special case for poll..
 */
static inline __poll_t inet_csk_listen_poll(const struct sock *sk)
{
        return !reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue) ?
                        (EPOLLIN | EPOLLRDNORM) : 0;
}

int inet_csk_listen_start(struct sock *sk);
void inet_csk_listen_stop(struct sock *sk);

/* update the fast reuse flag when adding a socket */
void inet_csk_update_fastreuse(const struct sock *sk,
                               struct inet_bind_bucket *tb,
                               struct inet_bind2_bucket *tb2);

struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu);

static inline void inet_csk_enter_pingpong_mode(struct sock *sk)
{
        inet_csk(sk)->icsk_ack.pingpong =
                READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_pingpong_thresh);
}

static inline void inet_csk_exit_pingpong_mode(struct sock *sk)
{
        inet_csk(sk)->icsk_ack.pingpong = 0;
}

static inline bool inet_csk_in_pingpong_mode(struct sock *sk)
{
        return inet_csk(sk)->icsk_ack.pingpong >=
               READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_pingpong_thresh);
}

static inline void inet_csk_inc_pingpong_cnt(struct sock *sk)
{
        struct inet_connection_sock *icsk = inet_csk(sk);

        if (icsk->icsk_ack.pingpong < U8_MAX)
                icsk->icsk_ack.pingpong++;
}

static inline bool inet_csk_has_ulp(const struct sock *sk)
{
        return inet_test_bit(IS_ICSK, sk) && !!inet_csk(sk)->icsk_ulp_ops;
}

static inline void inet_init_csk_locks(struct sock *sk)
{
        struct inet_connection_sock *icsk = inet_csk(sk);

        spin_lock_init(&icsk->icsk_accept_queue.rskq_lock);
        spin_lock_init(&icsk->icsk_accept_queue.fastopenq.lock);
}

#endif /* _INET_CONNECTION_SOCK_H */