1 files changed, 91 insertions, 0 deletions
diff --git a/src/timedata.cpp b/src/timedata.cpp
new file mode 100644
index 0000000000..8a095d26dc
--- /dev/null
+++ b/src/timedata.cpp
@@ -0,0 +1,91 @@
+// Copyright (c) 2014 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "timedata.h"
+
+#include "netbase.h"
+#include "sync.h"
+#include "ui_interface.h"
+#include "util.h"
+
+#include <boost/foreach.hpp>
+
+using namespace std;
+
+static CCriticalSection cs_nTimeOffset;
+static int64_t nTimeOffset = 0;
+
+//
+// "Never go to sea with two chronometers; take one or three."
+// Our three time sources are:
+//  - System clock
+//  - Median of other nodes clocks
+//  - The user (asking the user to fix the system clock if the first two disagree)
+//
+//
+int64_t GetTimeOffset()
+{
+    LOCK(cs_nTimeOffset);
+    return nTimeOffset;
+}
+
+int64_t GetAdjustedTime()
+{
+    return GetTime() + GetTimeOffset();
+}
+
+void AddTimeData(const CNetAddr& ip, int64_t nTime)
+{
+    int64_t nOffsetSample = nTime - GetTime();
+
+    LOCK(cs_nTimeOffset);
+    // Ignore duplicates
+    static set<CNetAddr> setKnown;
+    if (!setKnown.insert(ip).second)
+        return;
+
+    // Add data
+    static CMedianFilter<int64_t> vTimeOffsets(200,0);
+    vTimeOffsets.input(nOffsetSample);
+    LogPrintf("Added time data, samples %d, offset %+d (%+d minutes)\n", vTimeOffsets.size(), nOffsetSample, nOffsetSample/60);
+    if (vTimeOffsets.size() >= 5 && vTimeOffsets.size() % 2 == 1)
+    {
+        int64_t nMedian = vTimeOffsets.median();
+        std::vector<int64_t> vSorted = vTimeOffsets.sorted();
+        // Only let other nodes change our time by so much
+        if (abs64(nMedian) < 70 * 60)
+        {
+            nTimeOffset = nMedian;
+        }
+        else
+        {
+            nTimeOffset = 0;
+
+            static bool fDone;
+            if (!fDone)
+            {
+                // If nobody has a time different than ours but within 5 minutes of ours, give a warning
+                bool fMatch = false;
+                BOOST_FOREACH(int64_t nOffset, vSorted)
+                    if (nOffset != 0 && abs64(nOffset) < 5 * 60)
+                        fMatch = true;
+
+                if (!fMatch)
+                {
+                    fDone = true;
+                    string strMessage = _("Warning: Please check that your computer's date and time are correct! If your clock is wrong Bitcoin will not work properly.");
+                    strMiscWarning = strMessage;
+                    LogPrintf("*** %s\n", strMessage);
+                    uiInterface.ThreadSafeMessageBox(strMessage, "", CClientUIInterface::MSG_WARNING);
+                }
+            }
+        }
+        if (fDebug) {
+            BOOST_FOREACH(int64_t n, vSorted)
+                LogPrintf("%+d  ", n);
+            LogPrintf("|  ");
+        }
+        LogPrintf("nTimeOffset = %+d  (%+d minutes)\n", nTimeOffset, nTimeOffset/60);
+    }
+}