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 32 extern "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 */ 40 struct 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. */ 50 struct 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'. */ 70 int 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. */ 76 ev_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 */ 84 int 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 89 int 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