1 /*
2  * DTLS implementation written by Nagendra Modadugu
3  * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
4  */
5 /* ====================================================================
6  * Copyright (c) 1999-2005 The OpenSSL Project.  All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  *
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in
17  *    the documentation and/or other materials provided with the
18  *    distribution.
19  *
20  * 3. All advertising materials mentioning features or use of this
21  *    software must display the following acknowledgment:
22  *    "This product includes software developed by the OpenSSL Project
23  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
24  *
25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26  *    endorse or promote products derived from this software without
27  *    prior written permission. For written permission, please contact
28  *    openssl-core@OpenSSL.org.
29  *
30  * 5. Products derived from this software may not be called "OpenSSL"
31  *    nor may "OpenSSL" appear in their names without prior written
32  *    permission of the OpenSSL Project.
33  *
34  * 6. Redistributions of any form whatsoever must retain the following
35  *    acknowledgment:
36  *    "This product includes software developed by the OpenSSL Project
37  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
38  *
39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50  * OF THE POSSIBILITY OF SUCH DAMAGE.
51  * ====================================================================
52  *
53  * This product includes cryptographic software written by Eric Young
54  * (eay@cryptsoft.com).  This product includes software written by Tim
55  * Hudson (tjh@cryptsoft.com). */
56 
57 #ifndef OPENSSL_HEADER_PQUEUE_H
58 #define OPENSSL_HEADER_PQUEUE_H
59 
60 #include <openssl/base.h>
61 
62 #if defined(__cplusplus)
63 extern "C" {
64 #endif
65 
66 
67 /* Priority queue.
68  *
69  * The priority queue maintains a linked-list of nodes, each with a unique,
70  * 64-bit priority, in ascending priority order. */
71 
72 typedef struct _pqueue *pqueue;
73 
74 typedef struct _pitem {
75   uint8_t priority[8]; /* 64-bit value in big-endian encoding */
76   void *data;
77   struct _pitem *next;
78 } pitem;
79 
80 typedef struct _pitem *piterator;
81 
82 
83 /* Creating and freeing queues. */
84 
85 /* pqueue_new allocates a fresh, empty priority queue object and returns it, or
86  * NULL on error. */
87 OPENSSL_EXPORT pqueue pqueue_new(void);
88 
89 /* pqueue_free frees |pq| but not any of the items it points to. Thus |pq| must
90  * be empty or a memory leak will occur. */
91 OPENSSL_EXPORT void pqueue_free(pqueue pq);
92 
93 
94 /* Creating and freeing items. */
95 
96 /* pitem_new allocates a fresh priority queue item that points at |data| and
97  * has a priority given by |prio64be|, which is a 64-bit, unsigned number
98  * expressed in big-endian form. It returns the fresh item, or NULL on
99  * error. */
100 OPENSSL_EXPORT pitem *pitem_new(uint8_t prio64be[8], void *data);
101 
102 /* pitem_free frees |item|, but not any data that it points to. */
103 OPENSSL_EXPORT void pitem_free(pitem *item);
104 
105 
106 /* Queue accessor functions */
107 
108 /* pqueue_peek returns the item with the smallest priority from |pq|, or NULL
109  * if empty. */
110 OPENSSL_EXPORT pitem *pqueue_peek(pqueue pq);
111 
112 /* pqueue_find returns the item whose priority matches |prio64be| or NULL if no
113  * such item exists. */
114 OPENSSL_EXPORT pitem *pqueue_find(pqueue pq, uint8_t *prio64be);
115 
116 
117 /* Queue mutation functions */
118 
119 /* pqueue_insert inserts |item| into |pq| and returns item. */
120 OPENSSL_EXPORT pitem *pqueue_insert(pqueue pq, pitem *item);
121 
122 /* pqueue_pop takes the item with the least priority from |pq| and returns it,
123  * or NULL if |pq| is empty. */
124 OPENSSL_EXPORT pitem *pqueue_pop(pqueue pq);
125 
126 /* pqueue_size returns the number of items in |pq|. */
127 OPENSSL_EXPORT size_t pqueue_size(pqueue pq);
128 
129 
130 /* Iterating */
131 
132 /* pqueue_iterator returns an iterator that can be used to iterate over the
133  * contents of the queue. */
134 OPENSSL_EXPORT piterator pqueue_iterator(pqueue pq);
135 
136 /* pqueue_next returns the current value of |iter| and advances it to the next
137  * position. If the iterator has advanced over all the elements, it returns
138  * NULL. */
139 OPENSSL_EXPORT pitem *pqueue_next(piterator *iter);
140 
141 
142 #if defined(__cplusplus)
143 }  /* extern C */
144 #endif
145 
146 #endif  /* OPENSSL_HEADER_PQUEUE_H */
147