mirror of
https://github.com/ZeroTier/ZeroTierOne
synced 2025-07-30 11:39:29 -07:00
125 lines
3.4 KiB
C++
125 lines
3.4 KiB
C++
/*
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* ZeroTier One - Global Peer to Peer Ethernet
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* Copyright (C) 2012-2013 ZeroTier Networks LLC
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* --
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*
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* ZeroTier may be used and distributed under the terms of the GPLv3, which
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* are available at: http://www.gnu.org/licenses/gpl-3.0.html
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*
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* If you would like to embed ZeroTier into a commercial application or
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* redistribute it in a modified binary form, please contact ZeroTier Networks
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* LLC. Start here: http://www.zerotier.com/
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*/
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#ifndef _ZT_RATELIMITER_HPP
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#define _ZT_RATELIMITER_HPP
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#include <math.h>
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#include "Utils.hpp"
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namespace ZeroTier {
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/**
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* Burstable rate limiter
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*
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* This limits a transfer rate to a maximum bytes per second using an
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* accounting method based on a balance rather than accumulating an
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* average rate. The result is a burstable rate limit rather than a
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* continuous rate limit; the link being limited may use all its balance
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* at once or slowly over time. Balance constantly replenishes over time
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* up to a configurable maximum balance.
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*/
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class RateLimiter
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{
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public:
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/**
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* Create an uninitialized rate limiter
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*
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* init() must be called before this is used.
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*/
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RateLimiter() throw() {}
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/**
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* @param bytesPerSecond Bytes per second to permit (average)
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* @param preload Initial balance to place in account
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* @param max Maximum balance to permit to ever accrue (max burst)
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*/
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RateLimiter(double bytesPerSecond,double preload,double max)
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throw()
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{
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init(bytesPerSecond,preload,max);
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}
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/**
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* Initialize or re-initialize rate limiter
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*
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* @param bytesPerSecond Bytes per second to permit (average)
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* @param preload Initial balance to place in account
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* @param max Maximum balance to permit to ever accrue (max burst)
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*/
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inline void init(double bytesPerSecond,double preload,double max)
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throw()
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{
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_bytesPerSecond = bytesPerSecond;
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_lastTime = Utils::nowf();
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_balance = preload;
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_max = max;
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}
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/**
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* Update balance based on current clock
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*
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* This can be called at any time to check the current balance without
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* affecting the behavior of gate().
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*
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* @return New balance
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*/
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inline double updateBalance()
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throw()
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{
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double now = Utils::nowf();
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double b = _balance = fmin(_max,_balance + (_bytesPerSecond * (now - _lastTime)));
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_lastTime = now;
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return b;
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}
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/**
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* Test balance and update / deduct if there is enough to transfer 'bytes'
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*
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* @param bytes Number of bytes that we wish to transfer
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* @return True if balance was sufficient (balance is updated), false if not (balance unchanged)
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*/
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inline bool gate(double bytes)
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throw()
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{
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if (updateBalance() >= bytes) {
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_balance -= bytes;
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return true;
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}
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return false;
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}
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private:
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double _bytesPerSecond;
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double _lastTime;
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double _balance;
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double _max;
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};
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} // namespace ZeroTier
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#endif
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