mirror of
https://github.com/zerotier/ZeroTierOne.git
synced 2024-12-21 05:53:09 +00:00
151 lines
3.9 KiB
C++
151 lines
3.9 KiB
C++
/*
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* ZeroTier One - Network Virtualization Everywhere
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* Copyright (C) 2011-2015 ZeroTier, Inc.
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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_BWACCOUNT_HPP
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#define ZT_BWACCOUNT_HPP
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#include <stdint.h>
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#include <math.h>
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#include "Constants.hpp"
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#include "Utils.hpp"
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#ifdef __WINDOWS__
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#define round(x) ((x-floor(x))>0.5 ? ceil(x) : floor(x))
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#endif
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namespace ZeroTier {
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/**
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* Bandwidth account used for rate limiting multicast groups
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*
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* This is used to apply a bank account model to multicast groups. Each
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* multicast packet counts against a balance, which accrues at a given
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* rate in bytes per second. Debt is possible. These parameters are
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* configurable.
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*
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* A bank account model permits bursting behavior, which correctly models
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* how OSes and apps typically use multicast. It's common for things to
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* spew lots of multicast messages at once, wait a while, then do it
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* again. A consistent bandwidth limit model doesn't fit.
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*/
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class BandwidthAccount
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{
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public:
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/**
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* Create an uninitialized account
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*
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* init() must be called before this is used.
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*/
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BandwidthAccount() throw() {}
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/**
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* Create and initialize
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*
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* @param preload Initial balance to place in account
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* @param maxb Maximum allowed balance (> 0)
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* @param acc Rate of accrual in bytes per second
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* @param now Current time
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*/
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BandwidthAccount(uint32_t preload,uint32_t maxb,uint32_t acc,uint64_t now)
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throw()
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{
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init(preload,maxb,acc,now);
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}
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/**
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* Initialize or re-initialize account
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*
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* @param preload Initial balance to place in account
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* @param maxb Maximum allowed balance (> 0)
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* @param acc Rate of accrual in bytes per second
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* @param now Current time
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*/
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inline void init(uint32_t preload,uint32_t maxb,uint32_t acc,uint64_t now)
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throw()
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{
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_lastTime = ((double)now / 1000.0);
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_balance = preload;
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_maxBalance = maxb;
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_accrual = acc;
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}
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/**
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* Update and retrieve balance of this account
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*
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* @param now Current time
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* @return New balance updated from current clock
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*/
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inline uint32_t update(uint64_t now)
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throw()
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{
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double lt = _lastTime;
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double nowf = ((double)now / 1000.0);
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_lastTime = nowf;
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return (_balance = std::min(_maxBalance,(uint32_t)round((double)_balance + ((double)_accrual * (nowf - lt)))));
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}
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/**
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* Update balance and conditionally deduct
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*
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* If the deduction amount fits, it is deducted after update. Otherwise
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* balance is updated and false is returned.
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*
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* @param amt Amount to deduct
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* @param now Current time
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* @return True if amount fit within balance and was deducted
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*/
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inline bool deduct(uint32_t amt,uint64_t now)
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throw()
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{
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if (update(now) >= amt) {
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_balance -= amt;
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return true;
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}
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return false;
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}
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/**
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* @return Most recent balance without update
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*/
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inline uint32_t balance() const
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throw()
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{
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return _balance;
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}
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private:
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double _lastTime;
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uint32_t _balance;
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uint32_t _maxBalance;
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uint32_t _accrual;
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};
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} // namespace ZeroTier
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#endif
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