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 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 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