1// Copyright (c) 2024-present The Bitcoin Core developers
2// Distributed under the MIT software license, see the accompanying
3// file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5#include <node/timeoffsets.h>
6#include <node/warnings.h>
7#include <sync.h>
8#include <tinyformat.h>
9#include <util/log.h>
10#include <util/time.h>
11#include <util/translation.h>
12
13#include <algorithm>
14#include <chrono>
15#include <cstdint>
16#include <deque>
17#include <limits>
18#include <optional>
19
20using namespace std::chrono_literals;
21
22void TimeOffsets::Add(std::chrono::seconds offset)
23{
24    LOCK(m_mutex);
25
26    if (m_offsets.size() >= MAX_SIZE) {
27        m_offsets.pop_front();
28    }
29    m_offsets.push_back(offset);
30    LogDebug(BCLog::NET, "Added time offset %+ds, total samples %d\n",
31             Ticks<std::chrono::seconds>(offset), m_offsets.size());
32}
33
34std::chrono::seconds TimeOffsets::Median() const
35{
36    LOCK(m_mutex);
37
38    // Only calculate the median if we have 5 or more offsets
39    if (m_offsets.size() < 5) return 0s;
40
41    auto sorted_copy = m_offsets;
42    std::sort(sorted_copy.begin(), sorted_copy.end());
43    return sorted_copy[sorted_copy.size() / 2];  // approximate median is good enough, keep it simple
44}
45
46bool TimeOffsets::WarnIfOutOfSync() const
47{
48    // when median == std::numeric_limits<int64_t>::min(), calling std::chrono::abs is UB
49    auto median{std::max(Median(), std::chrono::seconds(std::numeric_limits<int64_t>::min() + 1))};
50    if (std::chrono::abs(median) <= WARN_THRESHOLD) {
51        m_warnings.Unset(node::Warning::CLOCK_OUT_OF_SYNC);
52        return false;
53    }
54
55    bilingual_str msg{strprintf(_(
56        "Your computer's date and time appear to be more than %d minutes out of sync with the network, "
57        "this may lead to consensus failure. After you've confirmed your computer's clock, this message "
58        "should no longer appear when you restart your node. Without a restart, it should stop showing "
59        "automatically after you've connected to a sufficient number of new outbound peers, which may "
60        "take some time. You can inspect the `timeoffset` field of the `getpeerinfo` and `getnetworkinfo` "
61        "RPC methods to get more info."
62    ), Ticks<std::chrono::minutes>(WARN_THRESHOLD))};
63    LogWarning("%s\n", msg.original);
64    m_warnings.Set(node::Warning::CLOCK_OUT_OF_SYNC, msg);
65    return true;
66}
67