/*-
 * Copyright (c) 2016-2018 Netflix, Inc.
 * All rights reserved.
 *
 * 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 AUTHOR 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 AUTHOR 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: Lawrence Stewart <lstewart@netflix.com>
 */

#include <sys/param.h>
#include <sys/arb.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/qmath.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#ifdef _KERNEL
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/rmlock.h>
#include <sys/systm.h>
#endif
#include <sys/stats.h>

#include <net/vnet.h>

#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/tcp.h>
#include <netinet/tcp_var.h>

#include <netinet/cc/cc.h>

VNET_DEFINE(int, tcp_perconn_stats_dflt_tpl) = -1;

#ifndef _KERNEL
#define V_tcp_perconn_stats_enable      VNET(tcp_perconn_stats_enable)
#define V_tcp_perconn_stats_dflt_tpl    VNET(tcp_perconn_stats_dflt_tpl)
#else /* _KERNEL */

VNET_DEFINE(int, tcp_perconn_stats_enable) = 2;
VNET_DEFINE_STATIC(struct stats_tpl_sample_rate *, tcp_perconn_stats_sample_rates);
VNET_DEFINE_STATIC(int, tcp_stats_nrates) = 0;
#define V_tcp_perconn_stats_sample_rates VNET(tcp_perconn_stats_sample_rates)
#define V_tcp_stats_nrates              VNET(tcp_stats_nrates)

static struct rmlock tcp_stats_tpl_sampling_lock;
static int tcp_stats_tpl_sr_cb(enum stats_tpl_sr_cb_action action,
    struct stats_tpl_sample_rate **rates, int *nrates, void *ctx);

SYSCTL_INT(_net_inet_tcp, OID_AUTO, perconn_stats_enable,
    CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_perconn_stats_enable), 0,
    "Enable per-connection TCP stats gathering; 1 enables for all connections, "
    "2 enables random sampling across log id connection groups");
SYSCTL_PROC(_net_inet_tcp, OID_AUTO, perconn_stats_sample_rates,
    CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_NEEDGIANT, tcp_stats_tpl_sr_cb,
    sizeof(struct rm_priotracker), stats_tpl_sample_rates, "A",
    "TCP stats per template random sampling rates, in CSV tpl_spec=percent "
    "key-value pairs (see stats(9) for template spec details)");
#endif /* _KERNEL */

#ifdef _KERNEL
int
#else
static int
/* Ensure all templates are also added to the userland template list. */
__attribute__ ((constructor))
#endif
tcp_stats_init(void)
{
        int err, lasterr;

        err = lasterr = 0;

        V_tcp_perconn_stats_dflt_tpl = stats_tpl_alloc("TCP_DEFAULT", 0);
        if (V_tcp_perconn_stats_dflt_tpl < 0)
                return (-V_tcp_perconn_stats_dflt_tpl);

        struct voistatspec vss_sum[] = {
                STATS_VSS_SUM(),
        };
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_TXPB, "TCP_TXPB", VSD_DTYPE_INT_U64,
            NVSS(vss_sum), vss_sum, 0);
        lasterr = err ? err : lasterr;
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_RETXPB, "TCP_RETXPB", VSD_DTYPE_INT_U32,
            NVSS(vss_sum), vss_sum, 0);
        lasterr = err ? err : lasterr;

        struct voistatspec vss_max[] = {
                STATS_VSS_MAX(),
        };
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_FRWIN, "TCP_FRWIN", VSD_DTYPE_INT_ULONG,
            NVSS(vss_max), vss_max, 0);
        lasterr = err ? err : lasterr;
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_LCWIN, "TCP_LCWIN", VSD_DTYPE_INT_ULONG,
            NVSS(vss_max), vss_max, 0);
        lasterr = err ? err : lasterr;

        struct voistatspec vss_rtt[] = {
                STATS_VSS_MAX(),
                STATS_VSS_MIN(),
                STATS_VSS_TDGSTCLUST32(20, 4),
        };
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_RTT, "TCP_RTT", VSD_DTYPE_INT_U32,
            NVSS(vss_rtt), vss_rtt, 0);
        lasterr = err ? err : lasterr;

        struct voistatspec vss_congsig[] = {
                STATS_VSS_DVHIST32_USR(HBKTS(DVBKT(CC_ECN), DVBKT(CC_RTO),
                    DVBKT(CC_RTO_ERR), DVBKT(CC_NDUPACK)), 0)
        };
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_CSIG, "TCP_CSIG", VSD_DTYPE_INT_U32,
            NVSS(vss_congsig), vss_congsig, 0);
        lasterr = err ? err : lasterr;

        struct voistatspec vss_gput[] = {
                STATS_VSS_MAX(),
                STATS_VSS_TDGSTCLUST32(20, 4),
        };
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_GPUT, "TCP_GPUT", VSD_DTYPE_INT_U32,
            NVSS(vss_gput), vss_gput, 0);
        lasterr = err ? err : lasterr;

        struct voistatspec vss_gput_nd[] = {
                STATS_VSS_TDGSTCLUST32(10, 4),
        };
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_GPUT_ND, "TCP_GPUT_ND", VSD_DTYPE_INT_S32,
            NVSS(vss_gput_nd), vss_gput_nd, 0);
        lasterr = err ? err : lasterr;

        struct voistatspec vss_windiff[] = {
                STATS_VSS_CRHIST32_USR(HBKTS(CRBKT(0)), VSD_HIST_LBOUND_INF)
        };
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_CALCFRWINDIFF, "TCP_CALCFRWINDIFF", VSD_DTYPE_INT_S32,
            NVSS(vss_windiff), vss_windiff, 0);
        lasterr = err ? err : lasterr;

        struct voistatspec vss_acklen[] = {
                STATS_VSS_MAX(),
                STATS_VSS_CRHIST32_LIN(0, 9, 1, VSD_HIST_UBOUND_INF)
        };
        err |= stats_tpl_add_voistats(V_tcp_perconn_stats_dflt_tpl,
            VOI_TCP_ACKLEN, "TCP_ACKLEN", VSD_DTYPE_INT_U32,
            NVSS(vss_acklen), vss_acklen, 0);
        lasterr = err ? err : lasterr;

        return (lasterr);
}

#ifdef _KERNEL
int
tcp_stats_sample_rollthedice(struct tcpcb *tp, void *seed_bytes,
    size_t seed_len)
{
        struct rm_priotracker tracker;
        int tpl;

        tpl = -1;

        if (V_tcp_stats_nrates > 0) {
                rm_rlock(&tcp_stats_tpl_sampling_lock, &tracker);
                tpl = stats_tpl_sample_rollthedice(V_tcp_perconn_stats_sample_rates,
                    V_tcp_stats_nrates, seed_bytes, seed_len);
                rm_runlock(&tcp_stats_tpl_sampling_lock, &tracker);

                if (tpl >= 0) {
                        INP_WLOCK_ASSERT(tptoinpcb(tp));
                        if (tp->t_stats != NULL)
                                stats_blob_destroy(tp->t_stats);
                        tp->t_stats = stats_blob_alloc(tpl, 0);
                        if (tp->t_stats == NULL)
                                tpl = -ENOMEM;
                }
        }

        return (tpl);
}

/*
 * Callback function for stats_tpl_sample_rates() to interact with the TCP
 * subsystem's stats template sample rates list.
 */
int
tcp_stats_tpl_sr_cb(enum stats_tpl_sr_cb_action action,
    struct stats_tpl_sample_rate **rates, int *nrates, void *ctx)
{
        struct stats_tpl_sample_rate *old_rates;
        int old_nrates;

        if (ctx == NULL)
                return (ENOMEM);

        switch (action) {
        case TPL_SR_RLOCKED_GET:
                /*
                 * Return with rlock held i.e. this call must be paired with a
                 * "action == TPL_SR_RUNLOCK" call.
                 */
                rm_assert(&tcp_stats_tpl_sampling_lock, RA_UNLOCKED);
                rm_rlock(&tcp_stats_tpl_sampling_lock,
                    (struct rm_priotracker *)ctx);
                /* FALLTHROUGH */
        case TPL_SR_UNLOCKED_GET:
                if (rates != NULL)
                        *rates = V_tcp_perconn_stats_sample_rates;
                if (nrates != NULL)
                        *nrates = V_tcp_stats_nrates;
                break;
        case TPL_SR_RUNLOCK:
                rm_assert(&tcp_stats_tpl_sampling_lock, RA_RLOCKED);
                rm_runlock(&tcp_stats_tpl_sampling_lock,
                    (struct rm_priotracker *)ctx);
                break;
        case TPL_SR_PUT:
                KASSERT(rates != NULL && nrates != NULL,
                    ("%s: PUT without new rates", __func__));
                rm_assert(&tcp_stats_tpl_sampling_lock, RA_UNLOCKED);
                if (rates == NULL || nrates == NULL)
                        return (EINVAL);
                rm_wlock(&tcp_stats_tpl_sampling_lock);
                old_rates = V_tcp_perconn_stats_sample_rates;
                old_nrates = V_tcp_stats_nrates;
                V_tcp_perconn_stats_sample_rates = *rates;
                V_tcp_stats_nrates = *nrates;
                rm_wunlock(&tcp_stats_tpl_sampling_lock);
                *rates = old_rates;
                *nrates = old_nrates;
                break;
        default:
                return (EINVAL);
                break;
        }

        return (0);
}

RM_SYSINIT(tcp_stats_tpl_sampling_lock, &tcp_stats_tpl_sampling_lock,
    "tcp_stats_tpl_sampling_lock");
#endif /* _KERNEL */