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https://github.com/XRPLF/rippled.git
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269 lines
9.3 KiB
C++
269 lines
9.3 KiB
C++
//------------------------------------------------------------------------------
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/*
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Copyright (c) 2011-2013, OpenCoin, Inc.
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*/
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//==============================================================================
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SETUP_LOG (SNTPClient)
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// #define SNTP_DEBUG
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static uint8_t SNTPQueryData[48] =
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{ 0x1B, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
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// NTP query frequency - 4 minutes
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#define NTP_QUERY_FREQUENCY (4 * 60)
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// NTP minimum interval to query same servers - 3 minutes
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#define NTP_MIN_QUERY (3 * 60)
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// NTP sample window (should be odd)
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#define NTP_SAMPLE_WINDOW 9
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// NTP timestamp constant
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#define NTP_UNIX_OFFSET 0x83AA7E80
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// NTP timestamp validity
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#define NTP_TIMESTAMP_VALID ((NTP_QUERY_FREQUENCY + NTP_MIN_QUERY) * 2)
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// SNTP packet offsets
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#define NTP_OFF_INFO 0
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#define NTP_OFF_ROOTDELAY 1
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#define NTP_OFF_ROOTDISP 2
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#define NTP_OFF_REFERENCEID 3
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#define NTP_OFF_REFTS_INT 4
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#define NTP_OFF_REFTS_FRAC 5
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#define NTP_OFF_ORGTS_INT 6
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#define NTP_OFF_ORGTS_FRAC 7
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#define NTP_OFF_RECVTS_INT 8
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#define NTP_OFF_RECVTS_FRAC 9
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#define NTP_OFF_XMITTS_INT 10
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#define NTP_OFF_XMITTS_FRAC 11
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SNTPClient::SNTPClient (boost::asio::io_service& service) : mSocket (service), mTimer (service), mResolver (service),
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mOffset (0), mLastOffsetUpdate ((time_t) - 1), mReceiveBuffer (256)
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{
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mSocket.open (boost::asio::ip::udp::v4 ());
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mSocket.async_receive_from (boost::asio::buffer (mReceiveBuffer, 256), mReceiveEndpoint,
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boost::bind (&SNTPClient::receivePacket, this, boost::asio::placeholders::error,
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boost::asio::placeholders::bytes_transferred));
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mTimer.expires_from_now (boost::posix_time::seconds (NTP_QUERY_FREQUENCY));
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mTimer.async_wait (boost::bind (&SNTPClient::timerEntry, this, boost::asio::placeholders::error));
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}
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void SNTPClient::resolveComplete (const boost::system::error_code& error, boost::asio::ip::udp::resolver::iterator it)
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{
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if (!error)
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{
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boost::asio::ip::udp::resolver::iterator sel = it;
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int i = 1;
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while (++it != boost::asio::ip::udp::resolver::iterator ())
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if ((rand () % ++i) == 0)
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sel = it;
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if (sel != boost::asio::ip::udp::resolver::iterator ())
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{
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boost::mutex::scoped_lock sl (mLock);
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SNTPQuery& query = mQueries[*sel];
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time_t now = time (NULL);
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if ((query.mLocalTimeSent == now) || ((query.mLocalTimeSent + 1) == now))
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{
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// This can happen if the same IP address is reached through multiple names
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WriteLog (lsTRACE, SNTPClient) << "SNTP: Redundant query suppressed";
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return;
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}
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query.mReceivedReply = false;
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query.mLocalTimeSent = now;
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RandomNumbers::getInstance ().fill (&query.mQueryNonce);
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reinterpret_cast<uint32*> (SNTPQueryData)[NTP_OFF_XMITTS_INT] = static_cast<uint32> (time (NULL)) + NTP_UNIX_OFFSET;
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reinterpret_cast<uint32*> (SNTPQueryData)[NTP_OFF_XMITTS_FRAC] = query.mQueryNonce;
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mSocket.async_send_to (boost::asio::buffer (SNTPQueryData, 48), *sel,
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boost::bind (&SNTPClient::sendComplete, this,
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boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred));
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}
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}
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}
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void SNTPClient::receivePacket (const boost::system::error_code& error, std::size_t bytes_xferd)
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{
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if (!error)
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{
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boost::mutex::scoped_lock sl (mLock);
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#ifdef SNTP_DEBUG
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WriteLog (lsTRACE, SNTPClient) << "SNTP: Packet from " << mReceiveEndpoint;
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#endif
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std::map<boost::asio::ip::udp::endpoint, SNTPQuery>::iterator query = mQueries.find (mReceiveEndpoint);
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if (query == mQueries.end ())
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WriteLog (lsDEBUG, SNTPClient) << "SNTP: Reply from " << mReceiveEndpoint << " found without matching query";
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else if (query->second.mReceivedReply)
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WriteLog (lsDEBUG, SNTPClient) << "SNTP: Duplicate response from " << mReceiveEndpoint;
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else
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{
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query->second.mReceivedReply = true;
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if (time (NULL) > (query->second.mLocalTimeSent + 1))
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WriteLog (lsWARNING, SNTPClient) << "SNTP: Late response from " << mReceiveEndpoint;
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else if (bytes_xferd < 48)
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WriteLog (lsWARNING, SNTPClient) << "SNTP: Short reply from " << mReceiveEndpoint
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<< " (" << bytes_xferd << ") " << mReceiveBuffer.size ();
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else if (reinterpret_cast<uint32*> (&mReceiveBuffer[0])[NTP_OFF_ORGTS_FRAC] != query->second.mQueryNonce)
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WriteLog (lsWARNING, SNTPClient) << "SNTP: Reply from " << mReceiveEndpoint << "had wrong nonce";
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else
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processReply ();
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}
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}
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mSocket.async_receive_from (boost::asio::buffer (mReceiveBuffer, 256), mReceiveEndpoint,
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boost::bind (&SNTPClient::receivePacket, this, boost::asio::placeholders::error,
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boost::asio::placeholders::bytes_transferred));
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}
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void SNTPClient::sendComplete (const boost::system::error_code& error, std::size_t)
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{
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CondLog (error, lsWARNING, SNTPClient) << "SNTP: Send error";
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}
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void SNTPClient::processReply ()
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{
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assert (mReceiveBuffer.size () >= 48);
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uint32* recvBuffer = reinterpret_cast<uint32*> (&mReceiveBuffer.front ());
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unsigned info = ntohl (recvBuffer[NTP_OFF_INFO]);
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int64_t timev = ntohl (recvBuffer[NTP_OFF_RECVTS_INT]);
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unsigned stratum = (info >> 16) & 0xff;
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if ((info >> 30) == 3)
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{
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WriteLog (lsINFO, SNTPClient) << "SNTP: Alarm condition " << mReceiveEndpoint;
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return;
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}
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if ((stratum == 0) || (stratum > 14))
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{
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WriteLog (lsINFO, SNTPClient) << "SNTP: Unreasonable stratum (" << stratum << ") from " << mReceiveEndpoint;
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return;
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}
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int64 now = static_cast<int> (time (NULL));
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timev -= now;
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timev -= NTP_UNIX_OFFSET;
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// add offset to list, replacing oldest one if appropriate
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mOffsetList.push_back (timev);
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if (mOffsetList.size () >= NTP_SAMPLE_WINDOW)
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mOffsetList.pop_front ();
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mLastOffsetUpdate = now;
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// select median time
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std::list<int> offsetList = mOffsetList;
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offsetList.sort ();
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int j = offsetList.size ();
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std::list<int>::iterator it = offsetList.begin ();
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for (int i = 0; i < (j / 2); ++i)
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++it;
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mOffset = *it;
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if ((j % 2) == 0)
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mOffset = (mOffset + (*--it)) / 2;
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if ((mOffset == -1) || (mOffset == 1)) // small corrections likely do more harm than good
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mOffset = 0;
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CondLog (timev || mOffset, lsTRACE, SNTPClient) << "SNTP: Offset is " << timev << ", new system offset is " << mOffset;
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}
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void SNTPClient::timerEntry (const boost::system::error_code& error)
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{
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if (!error)
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{
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doQuery ();
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mTimer.expires_from_now (boost::posix_time::seconds (NTP_QUERY_FREQUENCY));
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mTimer.async_wait (boost::bind (&SNTPClient::timerEntry, this, boost::asio::placeholders::error));
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}
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}
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void SNTPClient::addServer (const std::string& server)
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{
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boost::mutex::scoped_lock sl (mLock);
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mServers.push_back (std::make_pair (server, (time_t) - 1));
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}
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void SNTPClient::init (const std::vector<std::string>& servers)
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{
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std::vector<std::string>::const_iterator it = servers.begin ();
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if (it == servers.end ())
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{
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WriteLog (lsINFO, SNTPClient) << "SNTP: no server specified";
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return;
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}
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BOOST_FOREACH (const std::string & it, servers)
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addServer (it);
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queryAll ();
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}
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void SNTPClient::queryAll ()
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{
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while (doQuery ())
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nothing ();
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}
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bool SNTPClient::getOffset (int& offset)
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{
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boost::mutex::scoped_lock sl (mLock);
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if ((mLastOffsetUpdate == (time_t) - 1) || ((mLastOffsetUpdate + NTP_TIMESTAMP_VALID) < time (NULL)))
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return false;
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offset = mOffset;
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return true;
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}
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bool SNTPClient::doQuery ()
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{
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boost::mutex::scoped_lock sl (mLock);
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std::vector< std::pair<std::string, time_t> >::iterator best = mServers.end ();
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for (std::vector< std::pair<std::string, time_t> >::iterator it = mServers.begin (), end = best;
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it != end; ++it)
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if ((best == end) || (it->second == (time_t) - 1) || (it->second < best->second))
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best = it;
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if (best == mServers.end ())
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{
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WriteLog (lsTRACE, SNTPClient) << "SNTP: No server to query";
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return false;
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}
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time_t now = time (NULL);
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if ((best->second != (time_t) - 1) && ((best->second + NTP_MIN_QUERY) >= now))
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{
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WriteLog (lsTRACE, SNTPClient) << "SNTP: All servers recently queried";
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return false;
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}
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best->second = now;
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boost::asio::ip::udp::resolver::query query (boost::asio::ip::udp::v4 (), best->first, "ntp");
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mResolver.async_resolve (query,
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boost::bind (&SNTPClient::resolveComplete, this,
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boost::asio::placeholders::error, boost::asio::placeholders::iterator));
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#ifdef SNTP_DEBUG
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WriteLog (lsTRACE, SNTPClient) << "SNTP: Resolve pending for " << best->first;
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#endif
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return true;
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}
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// vim:ts=4
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