1/*	$NetBSD: ratelim-internal.h,v 1.5 2020/05/25 20:47:33 christos Exp $	*/
2
3/*
4 * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 *    derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28#ifndef RATELIM_INTERNAL_H_INCLUDED_
29#define RATELIM_INTERNAL_H_INCLUDED_
30
31#ifdef __cplusplus
32extern "C" {
33#endif
34
35#include "event2/util.h"
36
37/** A token bucket is an internal structure that tracks how many bytes we are
38 * currently willing to read or write on a given bufferevent or group of
39 * bufferevents */
40struct ev_token_bucket {
41	/** How many bytes are we willing to read or write right now? These
42	 * values are signed so that we can do "defecit spending" */
43	ev_ssize_t read_limit, write_limit;
44	/** When was this bucket last updated?  Measured in abstract 'ticks'
45	 * relative to the token bucket configuration. */
46	ev_uint32_t last_updated;
47};
48
49/** Configuration info for a token bucket or set of token buckets. */
50struct ev_token_bucket_cfg {
51	/** How many bytes are we willing to read on average per tick? */
52	size_t read_rate;
53	/** How many bytes are we willing to read at most in any one tick? */
54	size_t read_maximum;
55	/** How many bytes are we willing to write on average per tick? */
56	size_t write_rate;
57	/** How many bytes are we willing to write at most in any one tick? */
58	size_t write_maximum;
59
60	/* How long is a tick?  Note that fractions of a millisecond are
61	 * ignored. */
62	struct timeval tick_timeout;
63
64	/* How long is a tick, in milliseconds?  Derived from tick_timeout. */
65	unsigned msec_per_tick;
66};
67
68/** The current tick is 'current_tick': add bytes to 'bucket' as specified in
69 * 'cfg'. */
70int ev_token_bucket_update_(struct ev_token_bucket *bucket,
71    const struct ev_token_bucket_cfg *cfg,
72    ev_uint32_t current_tick);
73
74/** In which tick does 'tv' fall according to 'cfg'?  Note that ticks can
75 * overflow easily; your code needs to handle this. */
76ev_uint32_t ev_token_bucket_get_tick_(const struct timeval *tv,
77    const struct ev_token_bucket_cfg *cfg);
78
79/** Adjust 'bucket' to respect 'cfg', and note that it was last updated in
80 * 'current_tick'.  If 'reinitialize' is true, we are changing the
81 * configuration of 'bucket'; otherwise, we are setting it up for the first
82 * time.
83 */
84int ev_token_bucket_init_(struct ev_token_bucket *bucket,
85    const struct ev_token_bucket_cfg *cfg,
86    ev_uint32_t current_tick,
87    int reinitialize);
88
89int bufferevent_remove_from_rate_limit_group_internal_(struct bufferevent *bev,
90    int unsuspend);
91
92/** Decrease the read limit of 'b' by 'n' bytes */
93#define ev_token_bucket_decrement_read(b,n)	\
94	do {					\
95		(b)->read_limit -= (n);		\
96	} while (0)
97/** Decrease the write limit of 'b' by 'n' bytes */
98#define ev_token_bucket_decrement_write(b,n)	\
99	do {					\
100		(b)->write_limit -= (n);	\
101	} while (0)
102
103#ifdef __cplusplus
104}
105#endif
106
107#endif
108