1 /* $NetBSD: ratelim-internal.h,v 1.4 2021/04/10 19:02:37 rillig Exp $ */ 2 /* 3 * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 #ifndef RATELIM_INTERNAL_H_INCLUDED_ 28 #define RATELIM_INTERNAL_H_INCLUDED_ 29 30 #ifdef __cplusplus 31 extern "C" { 32 #endif 33 34 #include "event2/util.h" 35 36 /** A token bucket is an internal structure that tracks how many bytes we are 37 * currently willing to read or write on a given bufferevent or group of 38 * bufferevents */ 39 struct ev_token_bucket { 40 /** How many bytes are we willing to read or write right now? These 41 * values are signed so that we can do "defecit spending" */ 42 ev_ssize_t read_limit, write_limit; 43 /** When was this bucket last updated? Measured in abstract 'ticks' 44 * relative to the token bucket configuration. */ 45 ev_uint32_t last_updated; 46 }; 47 48 /** Configuration info for a token bucket or set of token buckets. */ 49 struct ev_token_bucket_cfg { 50 /** How many bytes are we willing to read on average per tick? */ 51 size_t read_rate; 52 /** How many bytes are we willing to read at most in any one tick? */ 53 size_t read_maximum; 54 /** How many bytes are we willing to write on average per tick? */ 55 size_t write_rate; 56 /** How many bytes are we willing to write at most in any one tick? */ 57 size_t write_maximum; 58 59 /* How long is a tick? Note that fractions of a millisecond are 60 * ignored. */ 61 struct timeval tick_timeout; 62 63 /* How long is a tick, in milliseconds? Derived from tick_timeout. */ 64 unsigned msec_per_tick; 65 }; 66 67 /** The current tick is 'current_tick': add bytes to 'bucket' as specified in 68 * 'cfg'. */ 69 int ev_token_bucket_update_(struct ev_token_bucket *bucket, 70 const struct ev_token_bucket_cfg *cfg, 71 ev_uint32_t current_tick); 72 73 /** In which tick does 'tv' fall according to 'cfg'? Note that ticks can 74 * overflow easily; your code needs to handle this. */ 75 ev_uint32_t ev_token_bucket_get_tick_(const struct timeval *tv, 76 const struct ev_token_bucket_cfg *cfg); 77 78 /** Adjust 'bucket' to respect 'cfg', and note that it was last updated in 79 * 'current_tick'. If 'reinitialize' is true, we are changing the 80 * configuration of 'bucket'; otherwise, we are setting it up for the first 81 * time. 82 */ 83 int ev_token_bucket_init_(struct ev_token_bucket *bucket, 84 const struct ev_token_bucket_cfg *cfg, 85 ev_uint32_t current_tick, 86 int reinitialize); 87 88 int bufferevent_remove_from_rate_limit_group_internal_(struct bufferevent *bev, 89 int unsuspend); 90 91 /** Decrease the read limit of 'b' by 'n' bytes */ 92 #define ev_token_bucket_decrement_read(b,n) \ 93 do { \ 94 (b)->read_limit -= (n); \ 95 } while (0) 96 /** Decrease the write limit of 'b' by 'n' bytes */ 97 #define ev_token_bucket_decrement_write(b,n) \ 98 do { \ 99 (b)->write_limit -= (n); \ 100 } while (0) 101 102 #ifdef __cplusplus 103 } 104 #endif 105 106 #endif 107