The 98th percentile position in the agebytes map was incorrectly
calculated: it assumed the transactions in the mempool all have unique
timestamps at second-granularity. This commit fixes this by correctly
finding the right cumulative number of transactions in the map suffix.
This bug could lead to an out-of-bounds write in the rare case that
all transactions in the mempool were received (and added to the mempool)
at a rate of at least 50 transactions per second. (More specifically,
the number of *unique* receive_time values, which have second-
granularity, must be at most 2% of the number of transactions in the
mempool for this crash to trigger.) If this condition is satisfied, 'it'
points to *before* the agebytes map, 'delta' gets a nonsense value, and
the value of 'i' in the first stats.histo-filling loop will be out of
bounds of stats.histo.
According to [1], std::random_shuffle is deprecated in C++14 and removed
in C++17. Since std::shuffle is available since C++11 as a replacement
and monero already requires C++11, this is a good replacement.
A cryptographically secure random number generator is used in all cases
to prevent people from perhaps copying an insecure std::shuffle call
over to a place where a secure one would be warranted. A form of
defense-in-depth.
[1]: https://en.cppreference.com/w/cpp/algorithm/random_shuffle
0605406 daemon: sort alt chains by height (moneromooo-monero)
4228ee0 daemon: add optional arguments to alt_chain_info (moneromooo-monero)
880ebfd daemon: add more chain specific info in alt_chain_info (moneromooo-monero)
35da33be blockchain: do not try to pop blocks down to the genesis block (moneromooo-monero)
4b51f9a3 core: do not commit half constructed batch db txn (moneromooo-monero)
d009f6dd rpc: fix get_block_hashes.bin from wallet on pruned blockchain (moneromooo-monero)
bb0ef5b1 blockchain: lock the blockchain while pruning (moneromooo-monero)
e9fac29a unit_tests/long_term_block_weight: some tweaks that seem to make more sense (stoffu)
467f4c7e tests/block_weight: use integer division when computing median (stoffu)
815d08dc tests/block_weight: remove unused MULTIPLIER_SMALL (stoffu)
661f1fb8 blockchain: remove unused calc of short_term_constraint (stoffu)
The db txn in add_block ending caused the entire overarching
batch txn to stop.
Also add a new guard class so a db txn can be stopped in the
face of exceptions.
Also use a read only db txn in init when the db itself is
read only, and do not save the max tx size in that case.
