d1c3762 Revert "Revert "Enable policy enforcing GetMedianTimePast as the end point of lock-time constraints"" (Gregory Maxwell)
e4e5334 Restore MedianTimePast for locktime. (Gregory Maxwell)
a6efc01 Bugfix: Omit wallet-related options from -help when wallet is disabled (Luke Dashjr)
5f9260f Bugfix: If genproclimit is omitted to RPC setgenerate, don't change it; also show correct default in getmininginfo (Luke Dashjr)
420a82f Bugfix: Describe dblogsize option correctly (it refers to the wallet database, not memory pool) (Luke Dashjr)
caa3d42 Bugfix: RPC: blockchain: Display correct defaults in help for verifychain method (Luke Dashjr)
Revert "Revert "Add rules--presently disabled--for using GetMedianTimePast as endpoint for lock-time calculations""
This reverts commit 40cd32e835.
After careful analysis it was determined that the change was, in fact, safe and several people were suffering
momentary confusion about locktime semantics.
This reverts commit 9d55050773.
As noted by Luke-Jr, under some conditions this will accept transactions which are invalid by the network
rules. This happens when the current block time is head of the median time past and a transaction's
locktime is in the middle.
This could be addressed by changing the rule to MAX(this_block_time, MTP+offset) but this solution and
the particular offset used deserve some consideration.
The lock-time code currently uses CBlock::nTime as the cutoff point for time based locked transactions. This has the unfortunate outcome of creating a perverse incentive for miners to lie about the time of a block in order to collect more fees by including transactions that by wall clock determination have not yet matured. By using CBlockIndex::GetMedianTimePast from the prior block instead, the self-interested miner no longer gains from generating blocks with fraudulent timestamps. Users can compensate for this change by simply adding an hour (3600 seconds) to their time-based lock times.
If enforced, this would be a soft-fork change. This commit only adds the functionality on an unexecuted code path, without changing the behaviour of Bitcoin Core.
After each transaction which is added to mempool, we first call
Expire() to remove old transactions, then throwing away the
lowest-feerate transactions.
After throwing away transactions by feerate, we set the minimum
relay fee to the maximum fee transaction-and-dependant-set we
removed, plus the default minimum relay fee.
After the next block is received, the minimum relay fee is allowed
to decrease exponentially. Its halflife defaults to 12 hours, but
is decreased to 6 hours if the mempool is smaller than half its
maximum size, and 3 hours if the mempool is smaller than a quarter
its maximum size.
The minimum -maxmempool size is 40*-limitdescendantsize, as it is
easy for an attacker to play games with the cheapest
-limitdescendantsize transactions. -maxmempool defaults to 300MB.
This disables high-priority transaction relay when the min relay
fee adjustment is >0 (ie when the mempool is full). When the relay
fee adjustment drops below the default minimum relay fee / 2 it is
set to 0 (re-enabling priority-based free relay).
(note the 9x multiplier on (void*)'s for CTxMemPool::DynamicMemoryUsage
was accidentally introduced in 5add7a7 but should have waited for this
commit which adds the extra index)
Associate with each CTxMemPoolEntry all the size/fees of descendant
mempool transactions. Sort mempool by max(feerate of entry, feerate
of descendants). Update statistics on-the-fly as transactions enter
or leave the mempool.
Also add ancestor and descendant limiting, so that transactions can
be rejected if the number or size of unconfirmed ancestors exceeds
a target, or if adding a transaction would cause some other mempool
entry to have too many (or too large) a set of unconfirmed in-
mempool descendants.
7f1f8f5 Move mempool rejections to new debug category (Wladimir J. van der Laan)
66daed5 Add information to errors in ConnectBlock, CheckBlock (Wladimir J. van der Laan)
6cab808 Remove most logging from transaction validation (Wladimir J. van der Laan)
9003c7c Add function to convert CValidationState to a human-readable message (Wladimir J. van der Laan)
dc58258 Introduce REJECT_INTERNAL codes for local AcceptToMempool errors (Wladimir J. van der Laan)
fbf44e6 Add debug message to CValidationState for optional extra information (Wladimir J. van der Laan)
Add status codes specific to AcceptToMempool procession of transactions.
These can never happen due to block validation, and must never be sent
over the P2P network. Add assertions where appropriate.
5922b67 Add assertion and cast before sending reject code (Wladimir J. van der Laan)
a651403 Add absurdly high fee message to validation state (for RPC propagation) (Shaul Kfir)
Make it possible to opt-out of the centralized alert system by providing
an option `-noalerts` or `-alerts=0`. The default remains unchanged.
This is a gentler form of #6260, in which I went a bit overboard by
removing the alert system completely.
I intend to add this to the GUI options in another pull after this.
The partition checking code was using chainActive timestamps
to detect partitioning; with headers-first syncing, it should use
(and with this pull request, does use) pIndexBestHeader timestamps.
Fixes issue #6251
Previously due to an off-by-one error the wallet ignored
nLockTime-by-height transactions that would be valid in the next block
even though they are accepted into the mempool. The transactions
wouldn't show up until confirmed, nor would they be included in the
unconfirmed balance. Similar to the mempool behavior fix in 665bdd3b,
the wallet code was calling IsFinalTx() directly without taking into
account the fact that doing so tells you if the transaction could have
been mined in the *current* block, rather than the next block.
To fix this we strip IsFinalTx() of non-consensus-critical
functionality, removing the default arguments, and add CheckFinalTx() to
check if a transaction will be final in the next block.
Create a monitoring task that counts how many blocks have been found in the last four hours.
If very few or too many have been found, an alert is triggered.
"Very few" and "too many" are set based on a false positive rate of once every fifty years of constant running with constant hashing power, which works out to getting 5 or fewer or 48 or more blocks in four hours (instead of the average of 24).
Only one alert per day is triggered, so if you get disconnected from the network (or are being Sybil'ed) -alertnotify will be triggered after 3.5 hours but you won't get another -alertnotify for 24 hours.
Tested with a new unit test and by running on the main network with -debug=partitioncheck
Run test/test_bitcoin --log_level=message to see the alert messages:
WARNING: check your network connection, 3 blocks received in the last 4 hours (24 expected)
WARNING: abnormally high number of blocks generated, 60 blocks received in the last 4 hours (24 expected)
The -debug=partitioncheck debug.log messages look like:
ThreadPartitionCheck : Found 22 blocks in the last 4 hours
ThreadPartitionCheck : likelihood: 0.0777702
a8cdaf5 checkpoints: move the checkpoints enable boolean into main (Cory Fields)
11982d3 checkpoints: Decouple checkpoints from Params (Cory Fields)
6996823 checkpoints: make checkpoints a member of CChainParams (Cory Fields)
9f13a10 checkpoints: store mapCheckpoints in CCheckpointData rather than a pointer (Cory Fields)
Wladimir J. van der Laan
Jorge Timón
MarcoFalke
Gregory Maxwell
Mark Friedenbach
Matt Corallo
Pieter Wuille
Luke Dashjr
Suhas Daftuar
Daniel Kraft
Shaul Kfir
Gavin Andresen
Philip Kaufmann
Peter Todd
Cory Fields