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