104 lines
4.6 KiB
Markdown
104 lines
4.6 KiB
Markdown
blockchain
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==========
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[](https://travis-ci.org/btcsuite/btcd)
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[](http://copyfree.org)
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[](http://godoc.org/github.com/btcsuite/btcd/blockchain)
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Package blockchain implements bitcoin block handling and chain selection rules.
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The test coverage is currently only around 60%, but will be increasing over
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time. See `test_coverage.txt` for the gocov coverage report. Alternatively, if
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you are running a POSIX OS, you can run the `cov_report.sh` script for a
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real-time report. Package blockchain is licensed under the liberal ISC license.
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There is an associated blog post about the release of this package
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[here](https://blog.conformal.com/btcchain-the-bitcoin-chain-package-from-bctd/).
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This package has intentionally been designed so it can be used as a standalone
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package for any projects needing to handle processing of blocks into the bitcoin
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block chain.
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## Installation and Updating
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```bash
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$ go get -u github.com/btcsuite/btcd/blockchain
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```
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## Bitcoin Chain Processing Overview
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Before a block is allowed into the block chain, it must go through an intensive
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series of validation rules. The following list serves as a general outline of
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those rules to provide some intuition into what is going on under the hood, but
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is by no means exhaustive:
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- Reject duplicate blocks
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- Perform a series of sanity checks on the block and its transactions such as
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verifying proof of work, timestamps, number and character of transactions,
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transaction amounts, script complexity, and merkle root calculations
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- Compare the block against predetermined checkpoints for expected timestamps
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and difficulty based on elapsed time since the checkpoint
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- Save the most recent orphan blocks for a limited time in case their parent
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blocks become available
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- Stop processing if the block is an orphan as the rest of the processing
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depends on the block's position within the block chain
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- Perform a series of more thorough checks that depend on the block's position
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within the block chain such as verifying block difficulties adhere to
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difficulty retarget rules, timestamps are after the median of the last
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several blocks, all transactions are finalized, checkpoint blocks match, and
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block versions are in line with the previous blocks
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- Determine how the block fits into the chain and perform different actions
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accordingly in order to ensure any side chains which have higher difficulty
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than the main chain become the new main chain
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- When a block is being connected to the main chain (either through
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reorganization of a side chain to the main chain or just extending the
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main chain), perform further checks on the block's transactions such as
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verifying transaction duplicates, script complexity for the combination of
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connected scripts, coinbase maturity, double spends, and connected
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transaction values
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- Run the transaction scripts to verify the spender is allowed to spend the
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coins
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- Insert the block into the block database
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## Examples
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* [ProcessBlock Example](http://godoc.org/github.com/btcsuite/btcd/blockchain#example-BlockChain-ProcessBlock)
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Demonstrates how to create a new chain instance and use ProcessBlock to
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attempt to add a block to the chain. This example intentionally
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attempts to insert a duplicate genesis block to illustrate how an invalid
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block is handled.
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* [CompactToBig Example](http://godoc.org/github.com/btcsuite/btcd/blockchain#example-CompactToBig)
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Demonstrates how to convert the compact "bits" in a block header which
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represent the target difficulty to a big integer and display it using the
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typical hex notation.
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* [BigToCompact Example](http://godoc.org/github.com/btcsuite/btcd/blockchain#example-BigToCompact)
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Demonstrates how to convert a target difficulty into the
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compact "bits" in a block header which represent that target difficulty.
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## GPG Verification Key
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All official release tags are signed by Conformal so users can ensure the code
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has not been tampered with and is coming from the btcsuite developers. To
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verify the signature perform the following:
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- Download the public key from the Conformal website at
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https://opensource.conformal.com/GIT-GPG-KEY-conformal.txt
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- Import the public key into your GPG keyring:
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```bash
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gpg --import GIT-GPG-KEY-conformal.txt
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```
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- Verify the release tag with the following command where `TAG_NAME` is a
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placeholder for the specific tag:
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```bash
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git tag -v TAG_NAME
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```
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## License
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Package blockchain is licensed under the [copyfree](http://copyfree.org) ISC
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License.
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