/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2009 Sam Leffler, Errno Consulting
 * 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 ``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 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.
 */

#include <sys/cdefs.h>
/*
 * IEEE 802.11 age queue support.
 */
#include "opt_wlan.h"

#include <sys/param.h>
#include <sys/systm.h> 
#include <sys/kernel.h>
#include <sys/malloc.h>

#include <sys/socket.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_media.h>
#include <net/ethernet.h>

#include <net80211/ieee80211_var.h>

/*
 * Initialize an ageq.
 */
void
ieee80211_ageq_init(struct ieee80211_ageq *aq, int maxlen, const char *name)
{
        memset(aq, 0, sizeof(*aq));
        aq->aq_maxlen = maxlen;
        IEEE80211_AGEQ_INIT(aq, name);          /* OS-dependent setup */
}

/*
 * Cleanup an ageq initialized with ieee80211_ageq_init.  Note
 * the queue is assumed empty; this can be done with ieee80211_ageq_drain.
 */
void
ieee80211_ageq_cleanup(struct ieee80211_ageq *aq)
{
        KASSERT(aq->aq_len == 0, ("%d frames on ageq", aq->aq_len));
        IEEE80211_AGEQ_DESTROY(aq);             /* OS-dependent cleanup */
}

/*
 * Free an mbuf according to ageq rules: if marked as holding
 * and 802.11 frame then also reclaim a node reference from
 * the packet header; this handles packets q'd in the tx path.
 */
static void
ageq_mfree(struct mbuf *m)
{
        if (m->m_flags & M_ENCAP) {
                struct ieee80211_node *ni = (void *) m->m_pkthdr.rcvif;
                ieee80211_free_node(ni);
        }
        m->m_nextpkt = NULL;
        m_freem(m);
}

/*
 * Free a list of mbufs using ageq rules (see above).
 */
void
ieee80211_ageq_mfree(struct mbuf *m)
{
        struct mbuf *next;

        for (; m != NULL; m = next) {
                next = m->m_nextpkt;
                ageq_mfree(m);
        }
}

/*
 * Append an mbuf to the ageq and mark it with the specified max age
 * If the frame is not removed before the age (in seconds) expires
 * then it is reclaimed (along with any node reference).
 */
int
ieee80211_ageq_append(struct ieee80211_ageq *aq, struct mbuf *m, int age)
{
        IEEE80211_AGEQ_LOCK(aq);
        if (__predict_true(aq->aq_len < aq->aq_maxlen)) {
                if (aq->aq_tail == NULL) {
                        aq->aq_head = m;
                } else {
                        aq->aq_tail->m_nextpkt = m;
                        age -= M_AGE_GET(aq->aq_head);
                }
                KASSERT(age >= 0, ("age %d", age));
                M_AGE_SET(m, age);
                m->m_nextpkt = NULL;
                aq->aq_tail = m;
                aq->aq_len++;
                IEEE80211_AGEQ_UNLOCK(aq);
                return 0;
        } else {
                /*
                 * No space, drop and cleanup references.
                 */
                aq->aq_drops++;
                IEEE80211_AGEQ_UNLOCK(aq);
                /* XXX tail drop? */
                ageq_mfree(m);
                return ENOSPC;
        }
}

/*
 * Drain/reclaim all frames from an ageq.
 */
void
ieee80211_ageq_drain(struct ieee80211_ageq *aq)
{
        ieee80211_ageq_mfree(ieee80211_ageq_remove(aq, NULL));
}

/*
 * Drain/reclaim frames associated with a specific node from an ageq.
 */
void
ieee80211_ageq_drain_node(struct ieee80211_ageq *aq,
        struct ieee80211_node *ni)
{
        ieee80211_ageq_mfree(ieee80211_ageq_remove(aq, ni));
}

/*
 * Age frames on the age queue.  Ages are stored as time
 * deltas (in seconds) relative to the head so we can check
 * and/or adjust only the head of the list.  If a frame's age
 * exceeds the time quanta then remove it.  The list of removed
 * frames is returned to the caller joined by m_nextpkt.
 */
struct mbuf *
ieee80211_ageq_age(struct ieee80211_ageq *aq, int quanta)
{
        struct mbuf *head, **phead;
        struct mbuf *m;

        phead = &head;
        if (aq->aq_len != 0) {
                IEEE80211_AGEQ_LOCK(aq);
                while ((m = aq->aq_head) != NULL && M_AGE_GET(m) < quanta) {
                        if ((aq->aq_head = m->m_nextpkt) == NULL)
                                aq->aq_tail = NULL;
                        KASSERT(aq->aq_len > 0, ("aq len %d", aq->aq_len));
                        aq->aq_len--;
                        /* add to private list for return */
                        *phead = m;
                        phead = &m->m_nextpkt;
                }
                if (m != NULL)
                        M_AGE_SUB(m, quanta);
                IEEE80211_AGEQ_UNLOCK(aq);
        }
        *phead = NULL;
        return head;
}

/*
 * Remove all frames matching the specified node identifier
 * (NULL matches all).  Frames are returned as a list joined
 * by m_nextpkt.
 */
struct mbuf *
ieee80211_ageq_remove(struct ieee80211_ageq *aq,
        struct ieee80211_node *match)
{
        struct mbuf *m, **prev, *ohead;
        struct mbuf *head, **phead;

        IEEE80211_AGEQ_LOCK(aq);
        ohead = aq->aq_head;
        prev = &aq->aq_head;
        phead = &head;
        while ((m = *prev) != NULL) {
                if (match != NULL && m->m_pkthdr.rcvif != (void *) match) {
                        prev = &m->m_nextpkt;
                        continue;
                }
                /*
                 * Adjust q length.
                 */
                KASSERT(aq->aq_len > 0, ("aq len %d", aq->aq_len));
                aq->aq_len--;
                /*
                 * Remove from forward list; tail pointer is harder.
                 */
                if (aq->aq_tail == m) {
                        KASSERT(m->m_nextpkt == NULL, ("not last"));
                        if (aq->aq_head == m) {         /* list empty */
                                KASSERT(aq->aq_len == 0,
                                    ("not empty, len %d", aq->aq_len));
                                aq->aq_tail = NULL;
                        } else {                        /* must be one before */
                                aq->aq_tail = (struct mbuf *)((uintptr_t)prev -
                                    offsetof(struct mbuf, m_nextpkt));
                        }
                }
                *prev = m->m_nextpkt;

                /* add to private list for return */
                *phead = m;
                phead = &m->m_nextpkt;
        }
        if (head == ohead && aq->aq_head != NULL)       /* correct age */
                M_AGE_SET(aq->aq_head, M_AGE_GET(head));
        IEEE80211_AGEQ_UNLOCK(aq);

        *phead = NULL;
        return head;
}