inet_connection_sock.h

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

#define INET_CSK_DEBUG 1

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

struct inet_bind_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 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)(struct sock *sk, struct sk_buff *skb,
                      struct request_sock *req,
                      struct dst_entry *dst);
    u16     net_header_len;
    u16     net_frag_header_len;
    u16     sockaddr_len;
    int     (*setsockopt)(struct sock *sk, int level, int optname, 
                  char __user *optval, unsigned int optlen);
    int     (*getsockopt)(struct sock *sk, int level, int optname, 
                  char __user *optval, int __user *optlen);
#ifdef CONFIG_COMPAT
    int     (*compat_setsockopt)(struct sock *sk,
                int level, int optname,
                char __user *optval, unsigned int optlen);
    int     (*compat_getsockopt)(struct sock *sk,
                int level, int optname,
                char __user *optval, int __user *optlen);
#endif
    void        (*addr2sockaddr)(struct sock *sk, struct sockaddr *);
    int     (*bind_conflict)(const struct sock *sk,
                     const struct inet_bind_bucket *tb, bool relax);
};

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;
    unsigned long         icsk_timeout;
    struct timer_list     icsk_retransmit_timer;
    struct timer_list     icsk_delack_timer;
    __u32             icsk_rto;
    __u32             icsk_pmtu_cookie;
    const struct tcp_congestion_ops *icsk_ca_ops;
    const struct inet_connection_sock_af_ops *icsk_af_ops;
    unsigned int          (*icsk_sync_mss)(struct sock *sk, u32 pmtu);
    __u8              icsk_ca_state;
    __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          blocked;   /* Delayed ACK was blocked by socket lock */
        __u32         ato;       /* Predicted tick of soft clock       */
        unsigned long     timeout;   /* Currently scheduled timeout        */
        __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 {
        int       enabled;

        /* Range of MTUs to search */
        int       search_high;
        int       search_low;

        /* Information on the current probe. */
        int       probe_size;
    } icsk_mtup;
    u32           icsk_ca_priv[16];
    u32           icsk_user_timeout;
#define ICSK_CA_PRIV_SIZE   (16 * sizeof(u32))
};

#define ICSK_TIME_RETRANS   1   /* Retransmit timer */
#define ICSK_TIME_DACK      2   /* Delayed ack timer */
#define ICSK_TIME_PROBE0    3   /* Zero window probe timer */

static inline struct inet_connection_sock *inet_csk(const struct sock *sk)
{
    return (struct inet_connection_sock *)sk;
}

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

extern 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
};

extern void inet_csk_init_xmit_timers(struct sock *sk,
                      void (*retransmit_handler)(unsigned long),
                      void (*delack_handler)(unsigned long),
                      void (*keepalive_handler)(unsigned long));
extern void inet_csk_clear_xmit_timers(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));
}

extern void inet_csk_delete_keepalive_timer(struct sock *sk);
extern void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long timeout);

#ifdef INET_CSK_DEBUG
extern const char inet_csk_timer_bug_msg[];
#endif

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) {
        icsk->icsk_pending = 0;
#ifdef INET_CSK_CLEAR_TIMERS
        sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
#endif
    } else if (what == ICSK_TIME_DACK) {
        icsk->icsk_ack.blocked = icsk->icsk_ack.pending = 0;
#ifdef INET_CSK_CLEAR_TIMERS
        sk_stop_timer(sk, &icsk->icsk_delack_timer);
#endif
    }
#ifdef INET_CSK_DEBUG
    else {
        pr_debug("%s", inet_csk_timer_bug_msg);
    }
#endif
}

/*
 *  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) {
#ifdef INET_CSK_DEBUG
        pr_debug("reset_xmit_timer: sk=%p %d when=0x%lx, caller=%p\n",
             sk, what, when, current_text_addr());
#endif
        when = max_when;
    }

    if (what == ICSK_TIME_RETRANS || what == ICSK_TIME_PROBE0) {
        icsk->icsk_pending = what;
        icsk->icsk_timeout = jiffies + when;
        sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout);
    } else if (what == ICSK_TIME_DACK) {
        icsk->icsk_ack.pending |= ICSK_ACK_TIMER;
        icsk->icsk_ack.timeout = jiffies + when;
        sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout);
    }
#ifdef INET_CSK_DEBUG
    else {
        pr_debug("%s", inet_csk_timer_bug_msg);
    }
#endif
}

extern struct sock *inet_csk_accept(struct sock *sk, int flags, int *err);

extern struct request_sock *inet_csk_search_req(const struct sock *sk,
                        struct request_sock ***prevp,
                        const __be16 rport,
                        const __be32 raddr,
                        const __be32 laddr);
extern int inet_csk_bind_conflict(const struct sock *sk,
                  const struct inet_bind_bucket *tb, bool relax);
extern int inet_csk_get_port(struct sock *sk, unsigned short snum);

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

static inline void inet_csk_reqsk_queue_add(struct sock *sk,
                        struct request_sock *req,
                        struct sock *child)
{
    reqsk_queue_add(&inet_csk(sk)->icsk_accept_queue, req, sk, child);
}

extern void inet_csk_reqsk_queue_hash_add(struct sock *sk,
                      struct request_sock *req,
                      unsigned long timeout);

static inline void inet_csk_reqsk_queue_removed(struct sock *sk,
                        struct request_sock *req)
{
    if (reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req) == 0)
        inet_csk_delete_keepalive_timer(sk);
}

static inline void inet_csk_reqsk_queue_added(struct sock *sk,
                          const unsigned long timeout)
{
    if (reqsk_queue_added(&inet_csk(sk)->icsk_accept_queue) == 0)
        inet_csk_reset_keepalive_timer(sk, timeout);
}

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_young(const struct sock *sk)
{
    return reqsk_queue_len_young(&inet_csk(sk)->icsk_accept_queue);
}

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

static inline void inet_csk_reqsk_queue_unlink(struct sock *sk,
                           struct request_sock *req,
                           struct request_sock **prev)
{
    reqsk_queue_unlink(&inet_csk(sk)->icsk_accept_queue, req, prev);
}

static inline void inet_csk_reqsk_queue_drop(struct sock *sk,
                         struct request_sock *req,
                         struct request_sock **prev)
{
    inet_csk_reqsk_queue_unlink(sk, req, prev);
    inet_csk_reqsk_queue_removed(sk, req);
    reqsk_free(req);
}

extern void inet_csk_reqsk_queue_prune(struct sock *parent,
                       const unsigned long interval,
                       const unsigned long timeout,
                       const unsigned long max_rto);

extern void inet_csk_destroy_sock(struct sock *sk);

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

extern int  inet_csk_listen_start(struct sock *sk, const int nr_table_entries);
extern void inet_csk_listen_stop(struct sock *sk);

extern void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr);

extern int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
                      char __user *optval, int __user *optlen);
extern int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
                      char __user *optval, unsigned int optlen);

extern struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu);
#endif /* _INET_CONNECTION_SOCK_H */