Simplify network-adjusted time warning logic

src/Makefile.am

@@ -233,6 +233,7 @@ BITCOIN_CORE_H = \
   node/peerman_args.h \
   node/protocol_version.h \
   node/psbt.h \
+  node/timeoffsets.h \
   node/transaction.h \
   node/txreconciliation.h \
   node/utxo_snapshot.h \
@@ -283,7 +284,6 @@ BITCOIN_CORE_H = \
   support/lockedpool.h \
   sync.h \
   threadsafety.h \
-  timedata.h \
   torcontrol.h \
   txdb.h \
   txmempool.h \
@@ -435,6 +435,7 @@ libbitcoin_node_a_SOURCES = \
   node/minisketchwrapper.cpp \
   node/peerman_args.cpp \
   node/psbt.cpp \
+  node/timeoffsets.cpp \
   node/transaction.cpp \
   node/txreconciliation.cpp \
   node/utxo_snapshot.cpp \
@@ -462,7 +463,6 @@ libbitcoin_node_a_SOURCES = \
   rpc/txoutproof.cpp \
   script/sigcache.cpp \
   signet.cpp \
-  timedata.cpp \
   torcontrol.cpp \
   txdb.cpp \
   txmempool.cpp \

src/Makefile.test.include

@@ -151,7 +151,7 @@ BITCOIN_TESTS =\
   test/streams_tests.cpp \
   test/sync_tests.cpp \
   test/system_tests.cpp \
-  test/timedata_tests.cpp \
+  test/timeoffsets_tests.cpp \
   test/torcontrol_tests.cpp \
   test/transaction_tests.cpp \
   test/translation_tests.cpp \
@@ -381,7 +381,7 @@ test_fuzz_fuzz_SOURCES = \
  test/fuzz/string.cpp \
  test/fuzz/strprintf.cpp \
  test/fuzz/system.cpp \
- test/fuzz/timedata.cpp \
+ test/fuzz/timeoffsets.cpp \
  test/fuzz/torcontrol.cpp \
  test/fuzz/transaction.cpp \
  test/fuzz/tx_in.cpp \

src/addrman_impl.h

@@ -11,7 +11,6 @@
 #include <protocol.h>
 #include <serialize.h>
 #include <sync.h>
-#include <timedata.h>
 #include <uint256.h>
 #include <util/time.h>
 

src/init.cpp

@@ -67,7 +67,6 @@
 #include <scheduler.h>
 #include <script/sigcache.h>
 #include <sync.h>
-#include <timedata.h>
 #include <torcontrol.h>
 #include <txdb.h>
 #include <txmempool.h>
@@ -523,7 +522,6 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-maxconnections=<n>", strprintf("Maintain at most <n> automatic connections to peers (default: %u). This limit does not apply to connections manually added via -addnode or the addnode RPC, which have a separate limit of %u.", DEFAULT_MAX_PEER_CONNECTIONS, MAX_ADDNODE_CONNECTIONS), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-maxreceivebuffer=<n>", strprintf("Maximum per-connection receive buffer, <n>*1000 bytes (default: %u)", DEFAULT_MAXRECEIVEBUFFER), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-maxsendbuffer=<n>", strprintf("Maximum per-connection memory usage for the send buffer, <n>*1000 bytes (default: %u)", DEFAULT_MAXSENDBUFFER), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
-    argsman.AddArg("-maxtimeadjustment", strprintf("Maximum allowed median peer time offset adjustment. Local perspective of time may be influenced by outbound peers forward or backward by this amount (default: %u seconds).", DEFAULT_MAX_TIME_ADJUSTMENT), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     argsman.AddArg("-maxuploadtarget=<n>", strprintf("Tries to keep outbound traffic under the given target per 24h. Limit does not apply to peers with 'download' permission or blocks created within past week. 0 = no limit (default: %s). Optional suffix units [k|K|m|M|g|G|t|T] (default: M). Lowercase is 1000 base while uppercase is 1024 base", DEFAULT_MAX_UPLOAD_TARGET), ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 #if HAVE_SOCKADDR_UN
     argsman.AddArg("-onion=<ip:port|path>", "Use separate SOCKS5 proxy to reach peers via Tor onion services, set -noonion to disable (default: -proxy). May be a local file path prefixed with 'unix:'.", ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);

src/net.cpp

@@ -599,7 +599,6 @@ void CNode::CopyStats(CNodeStats& stats)
     X(m_last_tx_time);
     X(m_last_block_time);
     X(m_connected);
-    X(nTimeOffset);
     X(m_addr_name);
     X(nVersion);
     {

src/net.h

@@ -191,7 +191,6 @@ class CNodeStats
     std::chrono::seconds m_last_tx_time;
     std::chrono::seconds m_last_block_time;
     std::chrono::seconds m_connected;
-    int64_t nTimeOffset;
     std::string m_addr_name;
     int nVersion;
     std::string cleanSubVer;
@@ -703,7 +702,6 @@ class CNode
     std::atomic<std::chrono::seconds> m_last_recv{0s};
     //! Unix epoch time at peer connection
     const std::chrono::seconds m_connected;
-    std::atomic<int64_t> nTimeOffset{0};
     // Address of this peer
     const CAddress addr;
     // Bind address of our side of the connection

src/net_processing.cpp

@@ -23,6 +23,7 @@
 #include <netbase.h>
 #include <netmessagemaker.h>
 #include <node/blockstorage.h>
+#include <node/timeoffsets.h>
 #include <node/txreconciliation.h>
 #include <policy/fees.h>
 #include <policy/policy.h>
@@ -34,7 +35,6 @@
 #include <scheduler.h>
 #include <streams.h>
 #include <sync.h>
-#include <timedata.h>
 #include <tinyformat.h>
 #include <txmempool.h>
 #include <txorphanage.h>
@@ -390,6 +390,10 @@ struct Peer {
     /** Whether this peer wants invs or headers (when possible) for block announcements */
     bool m_prefers_headers GUARDED_BY(NetEventsInterface::g_msgproc_mutex){false};
 
+    /** Time offset computed during the version handshake based on the
+     * timestamp the peer sent in the version message. */
+    std::atomic<std::chrono::seconds> m_time_offset{0s};
+
     explicit Peer(NodeId id, ServiceFlags our_services)
         : m_id{id}
         , m_our_services{our_services}
@@ -513,7 +517,7 @@ class PeerManagerImpl final : public PeerManager
     std::optional<std::string> FetchBlock(NodeId peer_id, const CBlockIndex& block_index) override
         EXCLUSIVE_LOCKS_REQUIRED(!m_peer_mutex);
     bool GetNodeStateStats(NodeId nodeid, CNodeStateStats& stats) const override EXCLUSIVE_LOCKS_REQUIRED(!m_peer_mutex);
-    bool IgnoresIncomingTxs() override { return m_opts.ignore_incoming_txs; }
+    PeerManagerInfo GetInfo() const override EXCLUSIVE_LOCKS_REQUIRED(!m_peer_mutex);
     void SendPings() override EXCLUSIVE_LOCKS_REQUIRED(!m_peer_mutex);
     void RelayTransaction(const uint256& txid, const uint256& wtxid) override EXCLUSIVE_LOCKS_REQUIRED(!m_peer_mutex);
     void SetBestBlock(int height, std::chrono::seconds time) override
@@ -749,6 +753,8 @@ class PeerManagerImpl final : public PeerManager
     /** Next time to check for stale tip */
     std::chrono::seconds m_stale_tip_check_time GUARDED_BY(cs_main){0s};
 
+    TimeOffsets m_outbound_time_offsets;
+
     const Options m_opts;
 
     bool RejectIncomingTxs(const CNode& peer) const;
@@ -1792,10 +1798,19 @@ bool PeerManagerImpl::GetNodeStateStats(NodeId nodeid, CNodeStateStats& stats) c
             stats.presync_height = peer->m_headers_sync->GetPresyncHeight();
         }
     }
+    stats.time_offset = peer->m_time_offset;
 
     return true;
 }
 
+PeerManagerInfo PeerManagerImpl::GetInfo() const
+{
+    return PeerManagerInfo{
+        .median_outbound_time_offset = m_outbound_time_offsets.Median(),
+        .ignores_incoming_txs = m_opts.ignore_incoming_txs,
+    };
+}
+
 void PeerManagerImpl::AddToCompactExtraTransactions(const CTransactionRef& tx)
 {
     if (m_opts.max_extra_txs <= 0)
@@ -3666,12 +3681,12 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
                   peer->m_starting_height, addrMe.ToStringAddrPort(), fRelay, pfrom.GetId(),
                   remoteAddr, (mapped_as ? strprintf(", mapped_as=%d", mapped_as) : ""));
 
-        int64_t nTimeOffset = nTime - GetTime();
-        pfrom.nTimeOffset = nTimeOffset;
+        peer->m_time_offset = NodeSeconds{std::chrono::seconds{nTime}} - Now<NodeSeconds>();
         if (!pfrom.IsInboundConn()) {
             // Don't use timedata samples from inbound peers to make it
-            // harder for others to tamper with our adjusted time.
-            AddTimeData(pfrom.addr, nTimeOffset);
+            // harder for others to create false warnings about our clock being out of sync.
+            m_outbound_time_offsets.Add(peer->m_time_offset);
+            m_outbound_time_offsets.WarnIfOutOfSync();
         }
 
         // If the peer is old enough to have the old alert system, send it the final alert.

src/net_processing.h

@@ -9,6 +9,8 @@
 #include <net.h>
 #include <validationinterface.h>
 
+#include <chrono>
+
 class AddrMan;
 class CChainParams;
 class CTxMemPool;
@@ -41,6 +43,12 @@ struct CNodeStateStats {
     bool m_addr_relay_enabled{false};
     ServiceFlags their_services;
     int64_t presync_height{-1};
+    std::chrono::seconds time_offset{0};
+};
+
+struct PeerManagerInfo {
+    std::chrono::seconds median_outbound_time_offset{0s};
+    bool ignores_incoming_txs{false};
 };
 
 class PeerManager : public CValidationInterface, public NetEventsInterface
@@ -83,8 +91,8 @@ class PeerManager : public CValidationInterface, public NetEventsInterface
     /** Get statistics from node state */
     virtual bool GetNodeStateStats(NodeId nodeid, CNodeStateStats& stats) const = 0;
 
-    /** Whether this node ignores txs received over p2p. */
-    virtual bool IgnoresIncomingTxs() = 0;
+    /** Get peer manager info. */
+    virtual PeerManagerInfo GetInfo() const = 0;
 
     /** Relay transaction to all peers. */
     virtual void RelayTransaction(const uint256& txid, const uint256& wtxid) = 0;

src/node/timeoffsets.cpp

@@ -0,0 +1,69 @@
+// Copyright (c) 2024-present The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <logging.h>
+#include <node/interface_ui.h>
+#include <node/timeoffsets.h>
+#include <sync.h>
+#include <tinyformat.h>
+#include <util/time.h>
+#include <util/translation.h>
+#include <warnings.h>
+
+#include <algorithm>
+#include <chrono>
+#include <cstdint>
+#include <deque>
+#include <limits>
+#include <optional>
+
+using namespace std::chrono_literals;
+
+void TimeOffsets::Add(std::chrono::seconds offset)
+{
+    LOCK(m_mutex);
+
+    if (m_offsets.size() >= MAX_SIZE) {
+        m_offsets.pop_front();
+    }
+    m_offsets.push_back(offset);
+    LogDebug(BCLog::NET, "Added time offset %+ds, total samples %d\n",
+             Ticks<std::chrono::seconds>(offset), m_offsets.size());
+}
+
+std::chrono::seconds TimeOffsets::Median() const
+{
+    LOCK(m_mutex);
+
+    // Only calculate the median if we have 5 or more offsets
+    if (m_offsets.size() < 5) return 0s;
+
+    auto sorted_copy = m_offsets;
+    std::sort(sorted_copy.begin(), sorted_copy.end());
+    return sorted_copy[sorted_copy.size() / 2];  // approximate median is good enough, keep it simple
+}
+
+bool TimeOffsets::WarnIfOutOfSync() const
+{
+    // when median == std::numeric_limits<int64_t>::min(), calling std::chrono::abs is UB
+    auto median{std::max(Median(), std::chrono::seconds(std::numeric_limits<int64_t>::min() + 1))};
+    if (std::chrono::abs(median) <= WARN_THRESHOLD) {
+        SetMedianTimeOffsetWarning(std::nullopt);
+        uiInterface.NotifyAlertChanged();
+        return false;
+    }
+
+    bilingual_str msg{strprintf(_(
+        "Your computer's date and time appear to be more than %d minutes out of sync with the network, "
+        "this may lead to consensus failure. After you've confirmed your computer's clock, this message "
+        "should no longer appear when you restart your node. Without a restart, it should stop showing "
+        "automatically after you've connected to a sufficient number of new outbound peers, which may "
+        "take some time. You can inspect the `timeoffset` field of the `getpeerinfo` and `getnetworkinfo` "
+        "RPC methods to get more info."
+    ), Ticks<std::chrono::minutes>(WARN_THRESHOLD))};
+    LogWarning("%s\n", msg.original);
+    SetMedianTimeOffsetWarning(msg);
+    uiInterface.NotifyAlertChanged();
+    return true;
+}

src/node/timeoffsets.h

@@ -0,0 +1,39 @@
+// Copyright (c) 2024-present The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_NODE_TIMEOFFSETS_H
+#define BITCOIN_NODE_TIMEOFFSETS_H
+
+#include <sync.h>
+
+#include <chrono>
+#include <cstddef>
+#include <deque>
+
+class TimeOffsets
+{
+    //! Maximum number of timeoffsets stored.
+    static constexpr size_t MAX_SIZE{50};
+    //! Minimum difference between system and network time for a warning to be raised.
+    static constexpr std::chrono::minutes WARN_THRESHOLD{10};
+
+    mutable Mutex m_mutex;
+    /** The observed time differences between our local clock and those of our outbound peers. A
+     * positive offset means our peer's clock is ahead of our local clock. */
+    std::deque<std::chrono::seconds> m_offsets GUARDED_BY(m_mutex){};
+
+public:
+    /** Add a new time offset sample. */
+    void Add(std::chrono::seconds offset) EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
+
+    /** Compute and return the median of the collected time offset samples. The median is returned
+     * as 0 when there are less than 5 samples. */
+    std::chrono::seconds Median() const EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
+
+    /** Raise warnings if the median time offset exceeds the warnings threshold. Returns true if
+     * warnings were raised. */
+    bool WarnIfOutOfSync() const EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
+};
+
+#endif // BITCOIN_NODE_TIMEOFFSETS_H

src/qt/guiutil.cpp

@@ -771,9 +771,9 @@ QString formatPingTime(std::chrono::microseconds ping_time)
         QObject::tr("%1 ms").arg(QString::number((int)(count_microseconds(ping_time) / 1000), 10));
 }
 
-QString formatTimeOffset(int64_t nTimeOffset)
+QString formatTimeOffset(int64_t time_offset)
 {
-  return QObject::tr("%1 s").arg(QString::number((int)nTimeOffset, 10));
+  return QObject::tr("%1 s").arg(QString::number((int)time_offset, 10));
 }
 
 QString formatNiceTimeOffset(qint64 secs)

src/qt/guiutil.h

@@ -240,8 +240,8 @@ namespace GUIUtil
     /** Format a CNodeStats.m_last_ping_time into a user-readable string or display N/A, if 0 */
     QString formatPingTime(std::chrono::microseconds ping_time);
 
-    /** Format a CNodeCombinedStats.nTimeOffset into a user-readable string */
-    QString formatTimeOffset(int64_t nTimeOffset);
+    /** Format a CNodeStateStats.time_offset into a user-readable string */
+    QString formatTimeOffset(int64_t time_offset);
 
     QString formatNiceTimeOffset(qint64 secs);
 

src/qt/rpcconsole.cpp

@@ -23,6 +23,7 @@
 #include <rpc/server.h>
 #include <util/strencodings.h>
 #include <util/string.h>
+#include <util/time.h>
 #include <util/threadnames.h>
 
 #include <univalue.h>
@@ -1196,7 +1197,6 @@ void RPCConsole::updateDetailWidget()
     ui->peerBytesRecv->setText(GUIUtil::formatBytes(stats->nodeStats.nRecvBytes));
     ui->peerPingTime->setText(GUIUtil::formatPingTime(stats->nodeStats.m_last_ping_time));
     ui->peerMinPing->setText(GUIUtil::formatPingTime(stats->nodeStats.m_min_ping_time));
-    ui->timeoffset->setText(GUIUtil::formatTimeOffset(stats->nodeStats.nTimeOffset));
     if (stats->nodeStats.nVersion) {
         ui->peerVersion->setText(QString::number(stats->nodeStats.nVersion));
     }
@@ -1228,6 +1228,7 @@ void RPCConsole::updateDetailWidget()
     // This check fails for example if the lock was busy and
     // nodeStateStats couldn't be fetched.
     if (stats->fNodeStateStatsAvailable) {
+        ui->timeoffset->setText(GUIUtil::formatTimeOffset(Ticks<std::chrono::seconds>(stats->nodeStateStats.time_offset)));
         ui->peerServices->setText(GUIUtil::formatServicesStr(stats->nodeStateStats.their_services));
         // Sync height is init to -1
         if (stats->nodeStateStats.nSyncHeight > -1) {

src/rpc/net.cpp

@@ -23,7 +23,6 @@
 #include <rpc/server_util.h>
 #include <rpc/util.h>
 #include <sync.h>
-#include <timedata.h>
 #include <util/chaintype.h>
 #include <util/strencodings.h>
 #include <util/string.h>
@@ -239,7 +238,7 @@ static RPCHelpMan getpeerinfo()
         obj.pushKV("bytessent", stats.nSendBytes);
         obj.pushKV("bytesrecv", stats.nRecvBytes);
         obj.pushKV("conntime", count_seconds(stats.m_connected));
-        obj.pushKV("timeoffset", stats.nTimeOffset);
+        obj.pushKV("timeoffset", Ticks<std::chrono::seconds>(statestats.time_offset));
         if (stats.m_last_ping_time > 0us) {
             obj.pushKV("pingtime", Ticks<SecondsDouble>(stats.m_last_ping_time));
         }
@@ -679,9 +678,10 @@ static RPCHelpMan getnetworkinfo()
         obj.pushKV("localservicesnames", GetServicesNames(services));
     }
     if (node.peerman) {
-        obj.pushKV("localrelay", !node.peerman->IgnoresIncomingTxs());
+        auto peerman_info{node.peerman->GetInfo()};
+        obj.pushKV("localrelay", !peerman_info.ignores_incoming_txs);
+        obj.pushKV("timeoffset", Ticks<std::chrono::seconds>(peerman_info.median_outbound_time_offset));
     }
-    obj.pushKV("timeoffset",    GetTimeOffset());
     if (node.connman) {
         obj.pushKV("networkactive", node.connman->GetNetworkActive());
         obj.pushKV("connections", node.connman->GetNodeCount(ConnectionDirection::Both));