1 /* $NetBSD: kern_rate.c,v 1.2 2012/12/12 11:10:56 pooka Exp $ */
2
3 /*-
4 * Copyright (c) 2000, 2004, 2005, 2007, 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christopher G. Demetriou.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __KERNEL_RCSID(0, "$NetBSD: kern_rate.c,v 1.2 2012/12/12 11:10:56 pooka Exp $");
34
35 #include <sys/param.h>
36 #include <sys/time.h>
37
38 /*
39 * ratecheck(): simple time-based rate-limit checking. see ratecheck(9)
40 * for usage and rationale.
41 */
42 int
ratecheck(struct timeval * lasttime,const struct timeval * mininterval)43 ratecheck(struct timeval *lasttime, const struct timeval *mininterval)
44 {
45 struct timeval tv, delta;
46 int rv = 0;
47
48 getmicrouptime(&tv);
49 timersub(&tv, lasttime, &delta);
50
51 /*
52 * check for 0,0 is so that the message will be seen at least once,
53 * even if interval is huge.
54 */
55 if (timercmp(&delta, mininterval, >=) ||
56 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
57 *lasttime = tv;
58 rv = 1;
59 }
60
61 return (rv);
62 }
63
64 /*
65 * ppsratecheck(): packets (or events) per second limitation.
66 */
67 int
ppsratecheck(struct timeval * lasttime,int * curpps,int maxpps)68 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps)
69 {
70 struct timeval tv, delta;
71 int rv;
72
73 getmicrouptime(&tv);
74 timersub(&tv, lasttime, &delta);
75
76 /*
77 * check for 0,0 is so that the message will be seen at least once.
78 * if more than one second have passed since the last update of
79 * lasttime, reset the counter.
80 *
81 * we do increment *curpps even in *curpps < maxpps case, as some may
82 * try to use *curpps for stat purposes as well.
83 */
84 if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) ||
85 delta.tv_sec >= 1) {
86 *lasttime = tv;
87 *curpps = 0;
88 }
89 if (maxpps < 0)
90 rv = 1;
91 else if (*curpps < maxpps)
92 rv = 1;
93 else
94 rv = 0;
95
96 #if 1 /*DIAGNOSTIC?*/
97 /* be careful about wrap-around */
98 if (__predict_true(*curpps != INT_MAX))
99 *curpps = *curpps + 1;
100 #else
101 /*
102 * assume that there's not too many calls to this function.
103 * not sure if the assumption holds, as it depends on *caller's*
104 * behavior, not the behavior of this function.
105 * IMHO it is wrong to make assumption on the caller's behavior,
106 * so the above #if is #if 1, not #ifdef DIAGNOSTIC.
107 */
108 *curpps = *curpps + 1;
109 #endif
110
111 return (rv);
112 }
113