/*-
 * Copyright (C) 2016 Centre for Advanced Internet Architectures,
 *  Swinburne University of Technology, Melbourne, Australia.
 * Portions of this code were made possible in part by a gift from 
 *  The Comcast Innovation Fund.
 * Implemented by Rasool Al-Saadi <ralsaadi@swin.edu.au>
 *
 * 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.
 */

/*
 * API for writing an Active Queue Management algorithm for Dummynet
 */

#ifndef _IP_DN_AQM_H
#define _IP_DN_AQM_H

#include <sys/ck.h>

/* NOW is the current time in millisecond*/
#define NOW ((V_dn_cfg.curr_time * tick) / 1000)

#define AQM_UNOW (V_dn_cfg.curr_time * tick)
#define AQM_TIME_1US ((aqm_time_t)(1))
#define AQM_TIME_1MS ((aqm_time_t)(1000))
#define AQM_TIME_1S ((aqm_time_t)(AQM_TIME_1MS * 1000))

/* aqm time allows to store up to 4294 seconds */
typedef uint32_t aqm_time_t;
typedef int32_t aqm_stime_t;

#define DN_AQM_MTAG_TS 55345

/* Macro for variable bounding */
#define BOUND_VAR(x,l,h)  ((x) > (h)? (h) : ((x) > (l)? (x) : (l)))

/*
 * Structure for holding data and function pointers that together represent a
 * AQM algorithm.
 */
 struct dn_aqm {
#define DN_AQM_NAME_MAX 50
        char                    name[DN_AQM_NAME_MAX];  /* name of AQM algorithm */
        uint32_t        type;   /* AQM type number */

        /* Methods implemented by AQM algorithm:
         * 
         * enqueue      enqueue packet 'm' on queue 'q'.
         *      Return 0 on success, 1 on drop.
         * 
         * dequeue      dequeue a packet from queue 'q'.
         *      Return a packet, NULL if no packet available.
         * 
         * config       configure AQM algorithm
         * If required, this function should allocate space to store 
         * the configurations and set 'fs->aqmcfg' to point to this space.
         * 'dn_extra_parms' includes array of parameters send
         * from ipfw userland command.
         *      Return 0 on success, non-zero otherwise.
         * 
         * deconfig     deconfigure AQM algorithm.
         * The allocated configuration memory space should be freed here.
         *      Return 0 on success, non-zero otherwise.
         * 
         * init initialise AQM status variables of queue 'q'
         * This function is used to allocate space and init AQM status for a
         * queue and q->aqm_status to point to this space.
         *      Return 0 on success, non-zero otherwise.
         * 
         * cleanup      cleanup AQM status variables of queue 'q'
         * The allocated memory space for AQM status should be freed here.
         *      Return 0 on success, non-zero otherwise.
         * 
         * getconfig    retrieve AQM configurations 
         * This function is used to return AQM parameters to userland
         * command. The function should fill 'dn_extra_parms' struct with 
         * the AQM configurations using 'par' array.
         * 
         */

        int (*enqueue)(struct dn_queue *, struct mbuf *);
        struct mbuf * (*dequeue)(struct dn_queue *);
        int (*config)(struct dn_fsk *, struct dn_extra_parms *ep, int);
        int (*deconfig)(struct dn_fsk *);
        int (*init)(struct dn_queue *);
        int (*cleanup)(struct dn_queue *);
        int (*getconfig)(struct dn_fsk *, struct dn_extra_parms *);

        int     ref_count; /*Number of queues instances in the system */
        int     cfg_ref_count;  /*Number of AQM instances in the system */
        CK_LIST_ENTRY(dn_aqm) next; /* Next AQM in the list */
};

/* Helper function to update queue and scheduler statistics.
 * negative len + drop -> drop
 * negative len -> dequeue
 * positive len -> enqueue
 * positive len + drop -> drop during enqueue
 */
__inline static void
update_stats(struct dn_queue *q, int len, int drop)
{
        int inc = 0;
        struct dn_flow *sni;
        struct dn_flow *qni;

        sni = &q->_si->ni;
        qni = &q->ni;

        if (len < 0)
                        inc = -1;
        else if(len > 0)
                        inc = 1;

        if (drop) {
                        qni->drops++;
                        sni->drops++;
                        V_dn_cfg.io_pkt_drop++;
        } else {
                /*update queue stats */
                qni->length += inc;
                qni->len_bytes += len;

                /*update scheduler instance stats */
                sni->length += inc;
                sni->len_bytes += len;
        }
        /* tot_pkts  is updated in dn_enqueue function */
}

/* kernel module related function */
int
dn_aqm_modevent(module_t mod, int cmd, void *arg);

#define DECLARE_DNAQM_MODULE(name, dnaqm)                       \
        static moduledata_t name##_mod = {                      \
                #name, dn_aqm_modevent, dnaqm           \
        };                                                      \
        DECLARE_MODULE(name, name##_mod,                        \
                SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);     \
        MODULE_DEPEND(name, dummynet, 3, 3, 3)

#endif