e457513eb1
0c85dc30e6p2p: Don't use timestamps from inbound peers (Martin Zumsande) Pull request description: `GetAdjustedTime()` (used e.g. in validation and addrman) returns a time with an offset that is influenced by timestamps that our peers have sent us in their version message. Currently, timestamps from all peers are used for this. However, I think that it would make sense to ignore the timedata samples from inbound peers, making it much harder for others to influence the Adjusted Time in a targeted way. With the extra feeler connections (every 2 minutes on average) and extra block-relay-only connections (every 5 minutes on average) there are also now plenty of opportunities to gather a meaningful number of timedata samples from outbound peers. There are some measures in place to prevent abuse: the `-maxtimeadjustment` parameter with a default of 70 minutes, warnings in cases of large deviations, only using the first 200 samples ([explanation](383d350bd5/src/timedata.cpp (L57-L72))), but I think that only using samples from outbound connections in the first place would be an additional safety measure that would make sense. See also issue #4521 for further context and links: There have been several discussions in the past about replacing or abolishing the existing timedata system. ACKs for top commit: jnewbery: Concept and code review ACK0c85dc30e6naumenkogs: ACK0c85dc30e6vasild: ACK0c85dc30e6Tree-SHA512: 2d6375305bcae034d68b58b7a07777b40ac430dfed554c88e681a048c527536691e1b7d08c0ef995247d356f8e81aa0a4b983bf2674faf6a416264e5f1af0a96
Bitcoin Core integration/staging tree
For an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/.
Further information about Bitcoin Core is available in the doc folder.
What is Bitcoin?
Bitcoin is an experimental digital currency that enables instant payments to anyone, anywhere in the world. Bitcoin uses peer-to-peer technology to operate with no central authority: managing transactions and issuing money are carried out collectively by the network. Bitcoin Core is the name of open source software which enables the use of this currency.
For more information read the original Bitcoin whitepaper.
License
Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/licenses/MIT.
Development Process
The master branch is regularly built (see doc/build-*.md for instructions) and tested, but it is not guaranteed to be
completely stable. Tags are created
regularly from release branches to indicate new official, stable release versions of Bitcoin Core.
The https://github.com/bitcoin-core/gui repository is used exclusively for the development of the GUI. Its master branch is identical in all monotree repositories. Release branches and tags do not exist, so please do not fork that repository unless it is for development reasons.
The contribution workflow is described in CONTRIBUTING.md and useful hints for developers can be found in doc/developer-notes.md.
Testing
Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.
Automated Testing
Developers are strongly encouraged to write unit tests for new code, and to
submit new unit tests for old code. Unit tests can be compiled and run
(assuming they weren't disabled in configure) with: make check. Further details on running
and extending unit tests can be found in /src/test/README.md.
There are also regression and integration tests, written
in Python.
These tests can be run (if the test dependencies are installed) with: test/functional/test_runner.py
The CI (Continuous Integration) systems make sure that every pull request is built for Windows, Linux, and macOS, and that unit/sanity tests are run automatically.
Manual Quality Assurance (QA) Testing
Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.
Translations
Changes to translations as well as new translations can be submitted to Bitcoin Core's Transifex page.
Translations are periodically pulled from Transifex and merged into the git repository. See the translation process for details on how this works.
Important: We do not accept translation changes as GitHub pull requests because the next pull from Transifex would automatically overwrite them again.