ad49c256c3
Split up util.cpp/h into: - string utilities (hex, base32, base64): no internal dependencies, no dependency on boost (apart from foreach) - money utilities (parsesmoney, formatmoney) - time utilities (gettime*, sleep, format date): - and the rest (logging, argument parsing, config file parsing) The latter is basically the environment and OS handling, and is stripped of all utility functions, so we may want to rename it to something else than util.cpp/h for clarity (Matt suggested osinterface). Breaks dependency of sha256.cpp on all the things pulled in by util.
116 lines
3.6 KiB
C++
116 lines
3.6 KiB
C++
// Copyright (c) 2014 The Bitcoin developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include "timedata.h"
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#include "netbase.h"
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#include "sync.h"
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#include "ui_interface.h"
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#include "util.h"
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#include "utilstrencodings.h"
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#include <boost/foreach.hpp>
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using namespace std;
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static CCriticalSection cs_nTimeOffset;
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static int64_t nTimeOffset = 0;
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//
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// "Never go to sea with two chronometers; take one or three."
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// Our three time sources are:
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// - System clock
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// - Median of other nodes clocks
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// - The user (asking the user to fix the system clock if the first two disagree)
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//
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//
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int64_t GetTimeOffset()
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{
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LOCK(cs_nTimeOffset);
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return nTimeOffset;
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}
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int64_t GetAdjustedTime()
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{
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return GetTime() + GetTimeOffset();
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}
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static int64_t abs64(int64_t n)
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{
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return (n >= 0 ? n : -n);
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}
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void AddTimeData(const CNetAddr& ip, int64_t nTime)
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{
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int64_t nOffsetSample = nTime - GetTime();
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LOCK(cs_nTimeOffset);
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// Ignore duplicates
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static set<CNetAddr> setKnown;
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if (!setKnown.insert(ip).second)
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return;
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// Add data
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static CMedianFilter<int64_t> vTimeOffsets(200,0);
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vTimeOffsets.input(nOffsetSample);
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LogPrintf("Added time data, samples %d, offset %+d (%+d minutes)\n", vTimeOffsets.size(), nOffsetSample, nOffsetSample/60);
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// There is a known issue here (see issue #4521):
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//
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// - The structure vTimeOffsets contains up to 200 elements, after which
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// any new element added to it will not increase its size, replacing the
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// oldest element.
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//
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// - The condition to update nTimeOffset includes checking whether the
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// number of elements in vTimeOffsets is odd, which will never happen after
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// there are 200 elements.
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//
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// But in this case the 'bug' is protective against some attacks, and may
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// actually explain why we've never seen attacks which manipulate the
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// clock offset.
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//
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// So we should hold off on fixing this and clean it up as part of
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// a timing cleanup that strengthens it in a number of other ways.
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//
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if (vTimeOffsets.size() >= 5 && vTimeOffsets.size() % 2 == 1)
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{
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int64_t nMedian = vTimeOffsets.median();
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std::vector<int64_t> vSorted = vTimeOffsets.sorted();
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// Only let other nodes change our time by so much
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if (abs64(nMedian) < 70 * 60)
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{
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nTimeOffset = nMedian;
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}
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else
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{
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nTimeOffset = 0;
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static bool fDone;
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if (!fDone)
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{
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// If nobody has a time different than ours but within 5 minutes of ours, give a warning
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bool fMatch = false;
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BOOST_FOREACH(int64_t nOffset, vSorted)
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if (nOffset != 0 && abs64(nOffset) < 5 * 60)
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fMatch = true;
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if (!fMatch)
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{
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fDone = true;
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string strMessage = _("Warning: Please check that your computer's date and time are correct! If your clock is wrong Bitcoin Core will not work properly.");
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strMiscWarning = strMessage;
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LogPrintf("*** %s\n", strMessage);
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uiInterface.ThreadSafeMessageBox(strMessage, "", CClientUIInterface::MSG_WARNING);
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}
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}
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}
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if (fDebug) {
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BOOST_FOREACH(int64_t n, vSorted)
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LogPrintf("%+d ", n);
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LogPrintf("| ");
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}
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LogPrintf("nTimeOffset = %+d (%+d minutes)\n", nTimeOffset, nTimeOffset/60);
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}
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}
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