/*-
 *
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2018-2020
 *      Netflix Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */
/**
 * Author: Randall Stewart <rrs@netflix.com>
 */
#ifndef __tcp_ratelimit_h__
#define __tcp_ratelimit_h__

struct m_snd_tag;

#define RL_MIN_DIVISOR 50
#define RL_DEFAULT_DIVISOR 1000

/* Flags on an individual rate */
#define HDWRPACE_INITED         0x0001
#define HDWRPACE_TAGPRESENT     0x0002
#define HDWRPACE_IFPDEPARTED    0x0004
struct tcp_hwrate_limit_table {
        const struct tcp_rate_set *ptbl;        /* Pointer to parent table */
        struct m_snd_tag *tag;  /* Send tag if needed (chelsio) */
        long     rate;          /* Rate we get in Bytes per second (Bps) */
        long     using;         /* How many flows are using this hdwr rate. */
        long     rs_num_enobufs;
        uint32_t time_between;  /* Time-Gap between packets at this rate */
        uint32_t flags;
};

/* Rateset flags */
#define RS_IS_DEFF      0x0001  /* Its a lagg, do a double lookup */
#define RS_IS_INTF      0x0002  /* Its a plain interface */
#define RS_NO_PRE       0x0004  /* The interfacd has set rates */
#define RS_INT_TBL      0x0010  /*
                                 * The table is the internal version
                                 * which has special setup requirements.
                                 */
#define RS_IS_DEAD      0x0020  /* The RS is dead list */
#define RS_FUNERAL_SCHD 0x0040  /* Is a epoch call scheduled to bury this guy?*/
#define RS_INTF_NO_SUP  0x0100  /* The interface does not support the ratelimiting */

struct tcp_rate_set {
        struct sysctl_ctx_list sysctl_ctx;
        CK_LIST_ENTRY(tcp_rate_set) next;
        struct ifnet *rs_ifp;
        struct tcp_hwrate_limit_table *rs_rlt;
        uint64_t rs_flows_using;
        uint64_t rs_flow_limit;
        uint32_t rs_if_dunit;
        int rs_rate_cnt;
        int rs_min_seg;
        int rs_highest_valid;
        int rs_lowest_valid;
        int rs_disable;
        int rs_flags;
        struct epoch_context rs_epoch_ctx;
};

CK_LIST_HEAD(head_tcp_rate_set, tcp_rate_set);

/* Request flags */
#define RS_PACING_EXACT_MATCH   0x0001  /* Need an exact match for rate */
#define RS_PACING_GT            0x0002  /* Greater than requested */
#define RS_PACING_GEQ           0x0004  /* Greater than or equal too */
#define RS_PACING_LT            0x0008  /* Less than requested rate */
#define RS_PACING_SUB_OK        0x0010  /* If a rate can't be found get the
                                         * next best rate (highest or lowest). */
#ifdef _KERNEL
#ifndef ETHERNET_SEGMENT_SIZE
#define ETHERNET_SEGMENT_SIZE 1514
#endif
struct tcpcb;

#ifdef RATELIMIT
#define DETAILED_RATELIMIT_SYSCTL 1     /*
                                         * Undefine this if you don't want
                                         * detailed rates to appear in
                                         * net.inet.tcp.rl.
                                         * With the defintion each rate
                                         * shows up in your sysctl tree
                                         * this can be big.
                                         */
uint64_t inline
tcp_hw_highest_rate(const struct tcp_hwrate_limit_table *rle)
{
        return (rle->ptbl->rs_rlt[rle->ptbl->rs_highest_valid].rate);
}

uint64_t
tcp_hw_highest_rate_ifp(struct ifnet *ifp, struct inpcb *inp);

const struct tcp_hwrate_limit_table *
tcp_set_pacing_rate(struct tcpcb *tp, struct ifnet *ifp,
    uint64_t bytes_per_sec, int flags, int *error, uint64_t *lower_rate);

const struct tcp_hwrate_limit_table *
tcp_chg_pacing_rate(const struct tcp_hwrate_limit_table *crte,
    struct tcpcb *tp, struct ifnet *ifp,
    uint64_t bytes_per_sec, int flags, int *error, uint64_t *lower_rate);
void
tcp_rel_pacing_rate(const struct tcp_hwrate_limit_table *crte,
    struct tcpcb *tp);

uint32_t
tcp_get_pacing_burst_size_w_divisor(struct tcpcb *tp, uint64_t bw, uint32_t segsiz, int can_use_1mss,
    const struct tcp_hwrate_limit_table *te, int *err, int divisor);

void
tcp_rl_log_enobuf(const struct tcp_hwrate_limit_table *rte);

void
tcp_rl_release_ifnet(struct ifnet *ifp);

#else
static inline const struct tcp_hwrate_limit_table *
tcp_set_pacing_rate(struct tcpcb *tp, struct ifnet *ifp,
    uint64_t bytes_per_sec, int flags, int *error, uint64_t *lower_rate)
{
        if (error)
                *error = EOPNOTSUPP;
        return (NULL);
}

static inline const struct tcp_hwrate_limit_table *
tcp_chg_pacing_rate(const struct tcp_hwrate_limit_table *crte,
    struct tcpcb *tp, struct ifnet *ifp,
    uint64_t bytes_per_sec, int flags, int *error, uint64_t *lower_rate)
{
        if (error)
                *error = EOPNOTSUPP;
        return (NULL);
}

static inline void
tcp_rel_pacing_rate(const struct tcp_hwrate_limit_table *crte,
    struct tcpcb *tp)
{
        return;
}

static uint64_t inline
tcp_hw_highest_rate(const struct tcp_hwrate_limit_table *rle)
{
        return (0);
}

static uint64_t inline
tcp_hw_highest_rate_ifp(struct ifnet *ifp, struct inpcb *inp)
{
        return (0);
}

static inline uint32_t
tcp_get_pacing_burst_size_w_divisor(struct tcpcb *tp, uint64_t bw, uint32_t segsiz, int can_use_1mss,
   const struct tcp_hwrate_limit_table *te, int *err, int divisor)
{
        /*
         * We use the google formula to calculate the
         * TSO size. I.E.
         * bw < 24Meg
         *   tso = 2mss
         * else
         *   tso = min(bw/(div=1000), 64k)
         *
         * Note for these calculations we ignore the
         * packet overhead (enet hdr, ip hdr and tcp hdr).
         * We only get the google formula when we have
         * divisor = 1000, which is the default for now.
         */
        uint64_t bytes;
        uint32_t new_tso, min_tso_segs;

        /* It can't be zero */
        if ((divisor == 0) ||
            (divisor < RL_MIN_DIVISOR)) {
                bytes = bw / RL_DEFAULT_DIVISOR;
        } else
                bytes = bw / divisor;
        /* We can't ever send more than 65k in a TSO */
        if (bytes > 0xffff) {
                bytes = 0xffff;
        }
        /* Round up */
        new_tso = (bytes + segsiz - 1) / segsiz;
        if (can_use_1mss)
                min_tso_segs = 1;
        else
                min_tso_segs = 2;
        if (new_tso < min_tso_segs)
                new_tso = min_tso_segs;
        new_tso *= segsiz;
        return (new_tso);
}

/* Do nothing if RATELIMIT is not defined */
static inline void
tcp_rl_log_enobuf(const struct tcp_hwrate_limit_table *rte)
{
}

static inline void
tcp_rl_release_ifnet(struct ifnet *ifp)
{
}
#endif

/*
 * Given a b/w and a segsiz, and optional hardware
 * rate limit, return the ideal size to burst
 * out at once. Note the parameter can_use_1mss
 * dictates if the transport will tolerate a 1mss
 * limit, if not it will bottom out at 2mss (think
 * delayed ack).
 */
static inline uint32_t
tcp_get_pacing_burst_size(struct tcpcb *tp, uint64_t bw, uint32_t segsiz, int can_use_1mss,
                          const struct tcp_hwrate_limit_table *te, int *err)
{

        return (tcp_get_pacing_burst_size_w_divisor(tp, bw, segsiz,
                                                    can_use_1mss,
                                                    te, err, 0));
}

#endif
#endif