Release Notes for Bitcoin Cash Node version 26.1.0

Bitcoin Cash Node version 26.1.0 is now available from:

https://bitcoincashnode.org

Overview

This release of Bitcoin Cash Node (BCHN) is a minor release.

It includes mostly bug fixes and performance enhancements, but there are some new features too, such as new fields in getpeerinfo RPC and new syntax variable for -walletnotify.

Usage recommendations

Users who are running v25.0.0 or v26.0.0 are encouraged to upgrade to v26.1.0 as it includes checkpoints and updated network static seeds for the recently completed (15 May 2023) network upgrade.

Network changes

Unsolicited ADDR messages from network peers are now rate-limited to an average rate of 0.1 addresses per second, with allowance for bursts of up to 1000 addresses.
This change should have no noticeable deleterious effect on the peer-to-peer network for well-behaved peers, and was merely added as a performance optimization.

Added functionality

None.

Deprecated functionality

None.

Modified functionality

• The getpeerinfo RPC method results now include two new additional data items for each peer: addr_processed and addr_rate_limited. See the getpeerinfo RPC help for a description of these new items.

• The -walletnotify option now understands an additional %-token: %w, which it will replace with the wallet name when executing the external command. For additional information see the help -hh for bitcoind.

• The current limit of 16 parallel script/sig verification threads, controlled by the -par configuration option, is substantially increased,
  to a maximum of 256 threads, with the following rules:

  • For users that do not use the -par argument/config, current legacy functionality is preserved (clamped to 16)
  • For users that set -par=0, their number of cores will be used (clamped to 256)
  • For users that set -par=N, with N a positive integer, the parallelism will be set to N, clamped to 256; note that users can set this higher than their core count, which preserves current functionality
  • For users that set -par=N, with N a negative integer, the parallelism will be set to leave N threads free, clamped to 256
  • For users using the GUI, the maximum number of threads they can set is equal to the number of cores, and is no longer 15 (sic!)
  • GUI users will not be able to set this limit to a number higher than their number of cores, via the slider.

  An upper limit is still needed, otherwise users can create thousands of threads and crash the node.

  The old limit of 16 was set 10 years ago when this functionality was first introduced. Since then both hardware and software have progressed vastly. Users should be able to set the parallelism higher if their hardware supports it. There may be diminishing returns setting it to higher than 16, but verification times do improve with more cores to an extent on modern platforms.

  NOTE 1: Current functionality is preserved only for users that don't use -par.

  NOTE 2: Only headless users can set -par above their core count.

Removed functionality

None.

New RPC methods

None.

User interface changes

• A bug in the fee rate override in the Send dialog of the GUI has been fixed.
• The dumpwallet file header comment now refers to "Bitcoin Cash Node",
• The importwallet progress bar behaves more sanely.
• Importing very large wallets has been made significantly faster.

Regressions

Bitcoin Cash Node 26.1.0 does not introduce any known regressions as compared to 26.0.0.

Limitations

The following are limitations in this release of which users should be aware:

1. CashToken support is low-level at this stage. The wallet application does not yet keep track of the user's tokens.
   Tokens are only manageable via RPC commands currently.
   They only persist through the UTXO database and block database at this point.
   There are existing RPC commands to list and filter for tokens in the UTXO set.
   RPC raw transaction handling commands have been extended to allow creation (and sending) of token transactions.
   Interested users are advised to consult the functional test in test/functional/bchn-rpc-tokens.py for examples on token transaction construction and listing.
   Future releases will aim to extend the RPC API with more convenient ways to create and spend tokens, as well as upgrading the wallet storage and indexing subsystems to persistently store data about tokens of interest to the user. Later we expect to add GUI wallet management of Cash Tokens.

2. Transactions with SIGHASH_UTXO are not covered by DSProofs at present.

3. P2SH-32 is not used by default in the wallet (regular P2SH-20 remains the default wherever P2SH is treated).

4. The markup of Double Spend Proof events in the wallet does not survive a restart of the wallet, as the information is not persisted to the wallet.

Known Issues

Some issues could not be closed in time for release, but we are tracking all of them on our GitLab repository.

• The minimum macOS version is 10.14 (Mojave). Earlier macOS versions are no longer supported.

• Windows users are recommended not to run multiple instances of bitcoin-qt or bitcoind on the same machine if the wallet feature is enabled. There is risk of data corruption if instances are configured to use the same wallet folder.

• Some users have encountered unit tests failures when running in WSL environments (e.g. WSL/Ubuntu). At this time, WSL is not considered a supported environment for the software. This may change in future.
  It has been reported that using WSL2 improves the issue.

• doc/dependencies.md needs revision (Issue #65).

• For users running from sources built with BerkeleyDB releases newer than the 5.3 which is used in this release, please take into consideration the database format compatibility issues described in Issue #34.
  When building from source it is recommended to use BerkeleyDB 5.3 as this avoids wallet database incompatibility issues with the official release.

• The test_bitcoin-qt test executable fails on Linux Mint 20 (see Issue #144). This does not otherwise appear to impact the functioning of the BCHN software on that platform.

• With a certain combination of build flags that included disabling the QR code library, a build failure was observed where an erroneous linking against the QR code library (not present) was attempted (Issue #138).

• Possible out-of-memory error when starting bitcoind with high excessiveblocksize value (Issue #156)

• A problem was observed on scalenet where nodes would sometimes hang for around 10 minutes, accepting RPC connections but not responding to them (see Issue #210).

• Startup and shutdown time of nodes on scalenet can be long (see Issue #313).

• Race condition in one of the p2p_invalid_messages.py tests (see Issue #409).

• Occasional failure in bchn-txbroadcastinterval.py (see Issue #403).

• wallet_keypool.py test failure when run as part of suite on certain many-core platforms (see Issue #380).

• Spurious 'insufficient funds' failure during p2p_stresstest.py benchmark (see Issue #377).

• If compiling from source, secp256k1 now no longer works with latest openssl3.x series.
  There are workarounds (see Issue #364).

• Spurious AssertionError: Mempool sync timed out in several tests (see Issue #357).

• For some platforms, there may be a need to install additional libraries in order to build from source (see Issue #431 and discussion in MR 1523).

• More TorV3 static seeds may be needed to get -onlynet=onion working (see Issue #429).

• Memory usage can be very high if repeatedly doing RPC getblock with verbose=2 on a hash of known big blocks (see Issue #466).

• Building / testing on current Arch Linux requires some additional package installations which are not yet reflected in the documentation. (see Issue #477).

• A GUI crash failure was observed when attempting to encrypt a large imported wallet (see Issue #490).

Changes since Bitcoin Cash Node 26.0.0

New documents

None.

Removed documents

None.

Notable commits grouped by functionality

Security or consensus relevant fixes

• 31ed5aa Fix issue with peers not receiving DSProofs if they ever use the mempool p2p message
• 5e8b41a Rate limit the Broadcast signal that gets spammed in SendMessages
• e661538 [net processing] ignore unknown INV types in GETDATA messages

Interfaces / RPC

• 39f8dfc wallet: Replace %w by wallet name in -walletnotify script
• 53e7d80 RPC: Fix dumpwallet comment/header to say "Bitcoin Cash Node"
• b8df878 Remove limit of 16 from -par

Features in internal development: support for UTXO commitments

• 3f8b0b0 Two small quality of life improvements (needed for utxosync work)

Data directory changes

None.

Performance optimizations

• 1ae0bb2 Performance fix: Modify logic slightly for the msghand thread sleeptime calc.
• 2b3ce0a Optimize two block reads with raw version
• 351daee Batch writes to wallet for rpc importwallet for faster imports
• 7ee3ad0 Add checkpoints post-upgrade9
• 86dd3ef Remove repeated calls to the slow gArgs object in perf. critical network code
• 9645fc8 Update chainparams assumevalid and minimumchainwork for 26.1.0
• a92f06e Remove redundant calls to GetTime*() in msghand thread
• f831cdb Reduce redundant copying for CCheckQueue (script check threads)

GUI

• 59f9780 Fix the fee rate override flag not being set when Send invoked in GUI
• 93805ba qt: Fix potential crash due to mis-use of showProgress
• ca155b3 [qt] Improve importwallet progress display

Code quality

• 2793192 refactor: remove references to deprecated values under std::allocator
• 3fa3105 trivial fix: Ensure HeapOptional move-constructor actually moves
• 428963c Refactor and docs for ProcessGetData
• 572676d nit: Use emplace_back in favor of push_back in CNode::ReceiveMsgBytes
• 5a20c2c Modify method HTTPReply::WriteReply to use Span<const uint8_t>
• 5bf58b2 Reduce redundant copying in the CScheduler class + other nits
• 5e8ed5a Update copyright year to 2023
• 7d840a6 Fix missing includes on GCC 13
• af2e452 Annotate some blockstorage & validation functions & data for thread-safety
• b549364 qa: Fixed a typo in synch.cpp

Documentation updates

• 0b0a035 Update release notes to talk about -walletnotify= and %w
• c61f448 [doc] Update testnet fork heights to reflect upgrade 9

Build / general

• b585ff8 [qa] Bump version to 26.1.0

Build / Linux

• 6b75a72 Fixes build errors on GCC 13
• aca0bc9 Fix for build failing on latest arch
• fcac1db [cmake] Fix a potential version mismatch in BerkeleyDB

Build / Windows

None.

Build / MacOSX

None.

Tests / test framework

• 533611f Fix for failing unit test
• d9df0e5 test: Check wallet name in -walletnotify script
• e016eb3 Fix intermittent "fee" related crash in rpc_blockchain.py

Benchmarks

• 715fe8e Update benchmarks in response to new verbosity mode TxVerbosity::SHOW_DETAILS_AND_PREVOUT
• 8b60b41 Add benchmark to test the speed of CNode::ReceiveMsgBytes
• 90ee323 bench: Refactor blockdata class

Seeds / seeder software

• 5bd1b9c Update regex'es in makeseeds.py after May 2023 upgrade
• 873f6dc Update static seeds for mainnet

Maintainer tools

None.

Infrastructure

None.

Cleanup

• 35d3bd2 Remove unused RPCSerializationFlags functionality
• 65d2acb Remove "zero after free" allocator from codebase (used by CDataStream)

Continuous Integration (GitLab CI)

None.

Backports

• 0b28311 backport: Disable unused special members functions in UnlockContext
• 1887c10 [backport] Rate-limit unsolicited p2p ADDR messages
• 398f0c0 backport: Fix potential use after move in validation.cpp
• 8c0de7d backport: Give WalletModel::UnlockContext move semantics
• cc520af [backport] Create blockstorage module