Release Notes for Bitcoin Cash Node version 22.0.0

Bitcoin Cash Node version 22.0.0 is now available from:

Overview

This is a major release of Bitcoin Cash Node that implements the November 15, 2020 Network Upgrade. This will upgrade the difficulty targeting used in Bitcoin Cash to a commonly agreed new algorithm called ASERT.

Additionally, this version contains many corrections and improvements.

User who are running any of our previous releases (0.21.x) are urged to upgrade to v22.0.0 well ahead of November 2020.

Usage recommendations

The update to Bitcoin Cash Node 22.0.0 is required for the November 15, 2020 Bitcoin Cash network upgrade.

Semantic version numbering

As of version 22.0.0, Bitcoin Cash Node uses Semantic Versioning for its version numbers. Hence our version numbers no longer start with a zero.

Semantic versioning makes it easy to tell from the change in version number what are the impacts on interfaces and backward compatibility:

A major version (first number) change indicates that an interface changed in a way that makes the new software incompatible with older releases.
A minor version change indicates added functionality that is backwards compatible.
A patch version (third number) change indicates that a new release only contains bug fixes which are backward compatible.

Network changes

Changes to automatic banning

Automatic banning of peers for bad behavior has been slightly altered:

Automatic bans are now referred to as "discouraged" in log output, as
they're not (and weren't even before) strictly banned: incoming connections
are still allowed from them (as was the case before this change), but they're
preferred for eviction.
Automatic bans will no longer time-out automatically after 24 hours.
Depending on traffic from other peers, automatic bans may time-out at an
indeterminate time.
Automatic bans will no longer be persisted across restarts. Only manual bans
will be persisted.
Automatic bans will no longer be returned by the listbanned RPC.
Automatic bans can no longer be lifted with the setban remove RPC command.
If you need to remove an automatic ban, you must clear all automatic bans with
the clearbanned false true RPC command, or restart the software to clear
automatic bans.
All extant automatic bans ("node misbehaving") that are currently stored in the
node's banlist.dat file will be converted into "manual bans" and will expire
within 24 hours after first running this version of BCHN.

Regtest network now requires standard transactions by default

The regression test chain, that can be enabled by the -regtest command line flag, now requires transactions to not violate standard policy by default. Making the default the same as for mainnet, makes it easier to test mainnet behavior on regtest. Be reminded that the testnet still allows non-standard
txs by default and that the policy can be locally adjusted with the -acceptnonstdtxn command line flag for both test chains.

Graceful expiration of this version on May 15, 2021

A mechanism has been added to this version such that it will gracefully expire on May 15, 2021, at the time of the network upgrade which is tentatively scheduled to occur then. Once this software expires, the RPC subsystem will disallow RPC commands. This feature can be disabled with the -expire=0 option. Furthermore, the date of expiration can be altered with the -tachyonactivationtime=<n> option.

This feature has been added as a safety measure to prevent this version of the node software from mining or otherwise transacting on an incompatible chain, should an upgrade take place on May 15th, 2021. This version will begin to warn via RPC "warnings", via a GUI message, and via periodic messages to the log starting 30 days prior to May 15th, 2021.

Once the future consensus rules of the May 15th, 2021 upgrade to the Bitcoin Cash network have been determined, a new version of Bitcoin Cash Node will be made available well in advance of May 15th, 2021. It is recommended that all users of Bitcoin Cash Node update their nodes at that time so as to ensure
uninterrupted operation.

Related configuration options:

-expire: Specify expire=0 in the configuration file or -expire=0 on the CLI to disable the aforementioned graceful expiration mechanism (default: 1).
-tachyonactivationtime=<n>: This option controls when the expiration mechanism (if enabled) will expire the node and disable RPC ( seconds since epoch, default: 1621080000).

Deprecated functionality

Autotools build system

The autotools build system (autogen, configure, ...) is deprecated and will be removed in a future release. CMake is the replacement build system, look at the documentation for the build instructions. To continue using the autotools build system, pass the --enable-deprecated-build-system flag to
configure.

CashAddr enabled by default in bitcoin-tx

The bitcoin-tx tool has fully supported CashAddr since v0.21.2. CashAddr in JSON output was disabled by default, but relying on this default was deprecated. Version 22.0.0 now changes the default to enabled. Specify -usecashaddr=0 to retain the old behavior.

Removed functionality

`medianfeerate` field removed from `getblockstats`

The medianfeerate field in getblockstats output has been removed. The 50th percentile from the feerate_percentiles array should be used instead.

`-datacarrier` removed

The bitcoind/bitcoin-qt option -datacarrier was deprecated in v0.21.2 and has now been removed in v22.0.0. Instead, use the existing option -datacarriersize to control relay and mining of OP_RETURN transactions, e.g. specify -datacarriersize=0 to reject them all.

BIP9 support removed

Bitcoin Cash Node 22.0.0 removed the (incomplete) BIP9 support. In earlier versions, it already was inactive due to no available proposals to vote on. The empty softforks field in getblockchaininfo has been removed.

Prototypical Avalanche removed

The Avalanche prototype features have been removed from this release pending specification and evaluation.

Windows 32-bit build removed

The 32-bit Windows target is no longer supported and has been removed from the release shipment.

Users that wish to build for 32 bits Windows should be aware that this will not be tested by the Bitcoin Cash Node team and be prepared to resolve issues on their own.

New RPC methods

No changes.

Low-level RPC changes

The sigops and sigoplimit values returned by the getblocktemplate
and getblocktemplatelight methods are now calculated according to the
SigChecks specification.
The clearbanned method now optionally can take two additional boolean
arguments (both default to true if unspecified). These arguments can be used
to control whether manual or automatic bans are to be cleared (or both).
The listbanned method no longer lists automatic bans.
The listbanned method's results array has changed slightly. All entries
now have their banned_reason as "manually added" (since listbanned can
now only ever show manual bans). The "node misbehaving" value for this key
will never appear. This key is now deprecated and may be removed altogether
in a future release of BCHN.
The setban method can no longer lift individual automatic bans. Use
clearbanned instead to clear all bans, or clearbanned false true to
clear all automatic bans (while preserving all manual bans).

Regressions

Bitcoin Cash Node 22.0.0 does not introduce any known regressions compared to 0.21.2.

Known Issues

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

MacOS versions earlier than 10.12 are no longer supported. Additionally,
Bitcoin Cash Node does not yet change appearance when macOS "dark mode"
is activated.
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.

The functional failure on WSL is tracked in Issue #33.
It arises when competing node program instances are not prevented from
opening the same wallet folder. Running multiple program instances with
the same configured walletdir could potentially lead to data corruption.
The failure has not been observed on other operating systems so far.
doc/dependencies.md needs revision (Issue #65).
arc lint will advise that some src/ files are in need of reformatting or
contain errors - this is because code style checking is currently a work in
progress while we adjust it to our own project requirements (see Issue #75).
One file in doc also violates the lint tool (Issue #153)
test_bitcoin can collide with temporary files if used by more than
one user on the same system simultaneously. (Issue #43)
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.
There is a documentation build bug that causes some ordered lists on
docs.bitcoincashnode.org to be rendered incorrectly (Issue #141).
There is a report that 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.
An 'autotools' build (the old build method) fails on OSX when using Clang.
(Issue #129)
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).
The 'autotools' build is known to require some workarounds in order to
use the 'fuzzing' build feature (Issue #127).

Changes since Bitcoin Cash Node 0.21.2

New documents

doc/bch-upgrades.md: List of all supported Bitcoin Cash upgrades
doc/coverage.md: Instructions to generate test coverage measurement

Removed documents

The documents in the doc/abc folder have been moved to the upgrade specifications document repository (https://upgradespecs.bitcoincashnode.org)

Notable commits grouped by functionality

Security or consensus relevant fixes

1a79646 Integer ASERT difficulty algorithm with 2-day half-life and MTP activation (aserti3-2d)
4f2478d BanManager: Reduce costly linear scans & modernize code

Interfaces / RPC

453795b Warn in RPC, Qt, and log as node approaches tachyon, disable RPC after tachyon
2fbd749 Remove legacy medianfeerate from getblockstats RPC
c920a58 Remove softforks field from getblockchaininfo RPC
52442c9 Remove -datacarrier CLI option
8ecbd3c Change -usecashaddr default to 1 in bitcoin-tx
b7c02a6 [backport] bitcoin-cli: Eliminate "Error parsing JSON" errors
5eb8875 Make getblockheader work with block height or block hash.
7de4551 Return hex encoding block header if verbose is set to false
7f0ad93 Unhide Axion (November) activation time parameter
9873ac4 UniValue fix: Serialize floats properly, irrespective of locale
fcf0ba5 Remove tr() calls and fix KB -> kB
83039f3 Fix CLI help text regressions

Peformance optimizations

4bdff70 Performance adjustments from review of backport of D5715
00e4609 Split UniValue::getValues() into getObjectValues() and getArrayValues()
b0edc7d Replace UniValue::exists() with find(), eliminate redundant object searches
b466250 Remove UniValue global function find_value
a58b4fb Performance: Optimized HexStr in util/strencodings.h
e23697d Store UniValue object keys and values together (#51 item 4)
69d0189 Nit to timedata.cpp: break out of loop when we get an answer
29b3eca uint256: Add an explicit "Uninitialized" constructor for performance
74bbc68 Base UniValue::setInt buffer size on maximum integer length

GUI

b48c870 [Qt] Fix debug screen size calculation

Code quality

77dee98 Remove incorrect right indentation from CLI help text
5687ff3 [qa] Fix issue 151 (code quality warning about undefined name)
3fa525a This is not experimental software
8f92174 Increase setexcessiveblock rpc example value to > current max blocksize
6d59b99 [lint] Adjust circular dependency expected list to our current baseline (removed 6 cycles)
e738a04 [lint] Break circular dependency between gbtlight and rpc/mining
048d061 Nits from review of D5756 backport
95d244b Remove unused UniValue::getObjMap()
79c307b Remove barely used UniValue::checkObject()
2db3bbe Modernized the code in the generated univalue_escapes.h file
e276c51 UniValue: removed superfluous inline keywords
1f41bbc Made UniValue::indentStr have a consistent declaration
24a6116 UniValue: Fix GCC compile warnings introduced by !464
017b6cf UniValue API additions: takeArrayValues(), front(), back(), operator== and more
9975aff [lint] Fix two Python linting issues in test/ which remained after MR485
9d298e8 GBTLight: Trivial fix to simplify the code in the unordered_map hasher
03df11e Code quality: Removed unused BEGIN, END, UBEGIN, and UEND macros
7de5ba6 Follow-up to MR !529 -- added better comments/naming
42d4344 Begin properly documenting the UniValue API
701faa5 Remove private method UniValue::findKey()
aeb6640 Expand MurmurHash3 API to accept any data type, not just std::vector
035bc17 Improve CRollingBloomFilter API to avoid double copies
a88ec3f UniValue: Fixed 2 small bugs, plus small performance improvement
d06c9d4 UniValue: Use std::snprintf in favor of ostringstream
d11532a Remove never used bool return values of UniValue methods
e2da2bd timedata.cpp nits: avoid extra copies, use thread safety macro
24c92ab wallet rpc: Fix to unused parameter caused by not passing coinControl down
6acd000 Fix missing #include <stdexcept> in univalue.cpp
39a4550 Remove UniValue::push_backV() and UniValue::pushKVs()
af68aef Fix double-copy and other minor nits seen in !591
0fbe779 Remove UniValue::clear()
813568d [rpc] Fix a few nits, unused parameters, and use std::move in rawtransaction.cpp
d8f7172 Simplify UniValue::write logic
c4281fb Fix unused function warning for GetPubKey in script/sign.cpp

Documentation updates

4dd54a7 Document implementation of November 2020 Bitcoin Cash Network Upgrade
490d710 Upgrade documentation of BIPs and BCH upgrades implementation history (#68)
64e2bf4 Update doc/ninja_targets.md
f841f99 [doc] Add lines before and after lists, and other Markdown doc improvements
504a3c1 Remove trailing spaces from generated Markdown documentation
e799876 [doc,lint] Remove trailing space in non-generated docs
c1d4225 [doc] Misc documentation fixes
4f33644 [doc] Document coverage targets
41ae1b7 [doc] Document tag 'gitian'
01e63ba [doc] Update documentation and 'pages' deployment to get rid of dead links
c649ee1 Adds part about building with WSL 2 (which has recently been released) and Ubuntu 20.04.
bbf6b19 [doc] Add git-lfs installation instructions
4ab5419 [doc] Add python dependency to OSX build
8ba2423 Restructure mkdocs navigation menu
4396c57 [doc] Update build-osx build guide
d1d9e16 Various Markdown fixes for proper display on docs.bitcoincashnode.org
9070d42 Fix Markdown in release notes too
652635a Added missing install in the dnf install command
e245c7c [doc] Add deprecation note for Win32 build and support
65da413 [Doc] How to run functional tests in an emulator
ddcfb45 [doc] Document AArch64 build

Build / general

8e6f6ad Use a versioned release notes link in the debian changelog file
7130d30 Update manpage generator for !540
e92388e [build] Improve error on sanitizer check failure

Build / Linux

b11ea17 [qa] Remove relocated Debian packaging scripts

Build / MacOSX