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blockchain: detect and log bad difficulty calculations

This commit is contained in:
moneromooo-monero 2020-05-16 20:11:40 +00:00
parent 309211fd6a
commit bb4d95c98f
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GPG Key ID: 686F07454D6CEFC3
1 changed files with 72 additions and 5 deletions
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77
src/cryptonote_core/blockchain.cpp
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@ -812,12 +812,20 @@ bool Blockchain::get_block_by_hash(const crypto::hash &h, block &blk, bool *orph
// less blocks than desired if there aren't enough.
difficulty_type Blockchain::get_difficulty_for_next_block()
{
LOG_PRINT_L3("Blockchain::" << __func__);
std::stringstream ss;
bool print = false;
int done = 0;
ss << "get_difficulty_for_next_block: height " << m_db->height() << std::endl;
if (m_fixed_difficulty)
{
return m_db->height() ? m_fixed_difficulty : 1;
}
LOG_PRINT_L3("Blockchain::" << __func__);
start:
difficulty_type D = 0;
crypto::hash top_hash = get_tail_id();
{
@ -826,21 +834,30 @@ difficulty_type Blockchain::get_difficulty_for_next_block()
// something a bit out of date, but that's fine since anything which
// requires the blockchain lock will have acquired it in the first place,
// and it will be unlocked only when called from the getinfo RPC
ss << "Locked, tail id " << top_hash << ", cached is " << m_difficulty_for_next_block_top_hash << std::endl;
if (top_hash == m_difficulty_for_next_block_top_hash)
return m_difficulty_for_next_block;
{
ss << "Same, using cached diff " << m_difficulty_for_next_block << std::endl;
D = m_difficulty_for_next_block;
}
}
CRITICAL_REGION_LOCAL(m_blockchain_lock);
std::vector<uint64_t> timestamps;
std::vector<difficulty_type> difficulties;
uint64_t height;
top_hash = get_tail_id(height); // get it again now that we have the lock
++height; // top block height to blockchain height
auto new_top_hash = get_tail_id(height); // get it again now that we have the lock
++height;
if (!(new_top_hash == top_hash)) D=0;
ss << "Re-locked, height " << height << ", tail id " << new_top_hash << (new_top_hash == top_hash ? "" : " (different)") << std::endl;
top_hash = new_top_hash;
// ND: Speedup
// 1. Keep a list of the last 735 (or less) blocks that is used to compute difficulty,
// then when the next block difficulty is queried, push the latest height data and
// pop the oldest one from the list. This only requires 1x read per height instead
// of doing 735 (DIFFICULTY_BLOCKS_COUNT).
bool check = false;
if (m_timestamps_and_difficulties_height != 0 && ((height - m_timestamps_and_difficulties_height) == 1) && m_timestamps.size() >= DIFFICULTY_BLOCKS_COUNT)
{
uint64_t index = height - 1;
@ -855,8 +872,12 @@ difficulty_type Blockchain::get_difficulty_for_next_block()
m_timestamps_and_difficulties_height = height;
timestamps = m_timestamps;
difficulties = m_difficulties;
check = true;
}
else
//else
std::vector<uint64_t> timestamps_from_cache = timestamps;
std::vector<difficulty_type> difficulties_from_cache = difficulties;
{
uint64_t offset = height - std::min <uint64_t> (height, static_cast<uint64_t>(DIFFICULTY_BLOCKS_COUNT));
if (offset == 0)
@ -869,22 +890,68 @@ difficulty_type Blockchain::get_difficulty_for_next_block()
timestamps.reserve(height - offset);
difficulties.reserve(height - offset);
}
ss << "Looking up " << (height - offset) << " from " << offset << std::endl;
for (; offset < height; offset++)
{
timestamps.push_back(m_db->get_block_timestamp(offset));
difficulties.push_back(m_db->get_block_cumulative_difficulty(offset));
}
if (check) if (timestamps != timestamps_from_cache || difficulties !=difficulties_from_cache)
{
ss << "Inconsistency XXX:" << std::endl;
ss << "top hash: "<<top_hash << std::endl;
ss << "timestamps: " << timestamps_from_cache.size() << " from cache, but " << timestamps.size() << " without" << std::endl;
ss << "difficulties: " << difficulties_from_cache.size() << " from cache, but " << difficulties.size() << " without" << std::endl;
ss << "timestamps_from_cache:" << std::endl; for (const auto &v :timestamps_from_cache) ss << " " << v << std::endl;
ss << "timestamps:" << std::endl; for (const auto &v :timestamps) ss << " " << v << std::endl;
ss << "difficulties_from_cache:" << std::endl; for (const auto &v :difficulties_from_cache) ss << " " << v << std::endl;
ss << "difficulties:" << std::endl; for (const auto &v :difficulties) ss << " " << v << std::endl;
uint64_t dbh = m_db->height();
uint64_t sh = dbh < 10000 ? 0 : dbh - 10000;
ss << "History from -10k at :" << dbh << ", from " << sh << std::endl;
for (uint64_t h = sh; h < dbh; ++h)
{
uint64_t ts = m_db->get_block_timestamp(h);
difficulty_type d = m_db->get_block_cumulative_difficulty(h);
ss << " " << h << " " << ts << " " << d << std::endl;
}
print = true;
}
m_timestamps_and_difficulties_height = height;
m_timestamps = timestamps;
m_difficulties = difficulties;
}
size_t target = get_difficulty_target();
difficulty_type diff = next_difficulty(timestamps, difficulties, target);
CRITICAL_REGION_LOCAL1(m_difficulty_lock);
m_difficulty_for_next_block_top_hash = top_hash;
m_difficulty_for_next_block = diff;
if (D && D != diff)
{
ss << "XXX Mismatch at " << height << "/" << top_hash << "/" << get_tail_id() << ": cached " << D << ", real " << diff << std::endl;
print = true;
}
++done;
if (done == 1 && D && D != diff)
{
print = true;
ss << "Might be a race. Let's see what happens if we try again..." << std::endl;
epee::misc_utils::sleep_no_w(100);
goto start;
}
ss << "Diff for " << top_hash << ": " << diff << std::endl;
if (print)
{
MGINFO("START DUMP");
MGINFO(ss.str());
MGINFO("END DUMP");
MGINFO("Please send moneromooo on Freenode the contents of this log, from a couple dozen lines before START DUMP to END DUMP");
}
return diff;
}
//------------------------------------------------------------------