/* $OpenBSD: pqueue.c,v 1.7 2025/05/04 10:53:38 tb Exp $ */
/*
 * DTLS implementation written by Nagendra Modadugu
 * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
 */
/* ====================================================================
 * Copyright (c) 1999-2005 The OpenSSL Project.  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.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED 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 OpenSSL PROJECT OR
 * ITS 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.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdlib.h>
#include <string.h>

#include "pqueue.h"

typedef struct _pqueue {
        pitem *items;
        int count;
} pqueue_s;

pitem *
pitem_new(const unsigned char *prio64be, void *data)
{
        pitem *item = malloc(sizeof(pitem));

        if (item == NULL)
                return NULL;

        memcpy(item->priority, prio64be, sizeof(item->priority));

        item->data = data;
        item->next = NULL;

        return item;
}

void
pitem_free(pitem *item)
{
        free(item);
}

pqueue_s *
pqueue_new(void)
{
        return calloc(1, sizeof(pqueue_s));
}

void
pqueue_free(pqueue_s *pq)
{
        free(pq);
}

pitem *
pqueue_insert(pqueue_s *pq, pitem *item)
{
        pitem *curr, *next;

        if (pq->items == NULL) {
                pq->items = item;
                return item;
        }

        for (curr = NULL, next = pq->items; next != NULL;
            curr = next, next = next->next) {
                /* we can compare 64-bit value in big-endian encoding
                 * with memcmp:-) */
                int cmp = memcmp(next->priority, item->priority,
                    sizeof(item->priority));
                if (cmp > 0) {          /* next > item */
                        item->next = next;

                        if (curr == NULL)
                                pq->items = item;
                        else
                                curr->next = item;

                        return item;
                } else if (cmp == 0)    /* duplicates not allowed */
                        return NULL;
        }

        item->next = NULL;
        curr->next = item;

        return item;
}

pitem *
pqueue_peek(pqueue_s *pq)
{
        return pq->items;
}

pitem *
pqueue_pop(pqueue_s *pq)
{
        pitem *item = pq->items;

        if (pq->items != NULL)
                pq->items = pq->items->next;

        return item;
}

pitem *
pqueue_find(pqueue_s *pq, const unsigned char *prio64be)
{
        pitem *next;

        for (next = pq->items; next != NULL; next = next->next)
                if (memcmp(next->priority, prio64be,
                    sizeof(next->priority)) == 0)
                        return next;

        return NULL;
}

pitem *
pqueue_iterator(pqueue_s *pq)
{
        return pqueue_peek(pq);
}

pitem *
pqueue_next(pitem **item)
{
        pitem *ret;

        if (item == NULL || *item == NULL)
                return NULL;

        /* *item != NULL */
        ret = *item;
        *item = (*item)->next;

        return ret;
}

int
pqueue_size(pqueue_s *pq)
{
        pitem *item = pq->items;
        int count = 0;

        while (item != NULL) {
                count++;
                item = item->next;
        }
        return count;
}