b69a849114
This commit contains the entire btcchain repository along with several changes needed to move all of the files into the blockchain directory in order to prepare it for merging. This does NOT update btcd or any of the other packages to use the new location as that will be done separately. - All import paths in the old btcchain test files have been changed to the new location - All references to btcchain as the package name have been changed to blockchain
81 lines
4.1 KiB
Go
81 lines
4.1 KiB
Go
// Copyright (c) 2013-2014 Conformal Systems LLC.
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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/*
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Package blockchain implements bitcoin block handling and chain selection rules.
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The bitcoin block handling and chain selection rules are an integral, and quite
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likely the most important, part of bitcoin. Unfortunately, at the time of
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this writing, these rules are also largely undocumented and had to be
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ascertained from the bitcoind source code. At its core, bitcoin is a
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distributed consensus of which blocks are valid and which ones will comprise the
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main block chain (public ledger) that ultimately determines accepted
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transactions, so it is extremely important that fully validating nodes agree on
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all rules.
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At a high level, this package provides support for inserting new blocks into
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the block chain according to the aforementioned rules. It includes
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functionality such as rejecting duplicate blocks, ensuring blocks and
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transactions follow all rules, orphan handling, and best chain selection along
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with reorganization.
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Since this package does not deal with other bitcoin specifics such as network
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communication or wallets, it provides a notification system which gives the
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caller a high level of flexibility in how they want to react to certain events
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such as orphan blocks which need their parents requested and newly connected
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main chain blocks which might result in wallet updates.
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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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Errors
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Errors returned by this package are either the raw errors provided by underlying
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calls or of type blockchain.RuleError. This allows the caller to differentiate
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between unexpected errors, such as database errors, versus errors due to rule
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violations through type assertions. In addition, callers can programmatically
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determine the specific rule violation by examining the ErrorCode field of the
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type asserted blockchain.RuleError.
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Bitcoin Improvement Proposals
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This package includes spec changes outlined by the following BIPs:
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BIP0016 (https://en.bitcoin.it/wiki/BIP_0016)
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BIP0030 (https://en.bitcoin.it/wiki/BIP_0030)
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BIP0034 (https://en.bitcoin.it/wiki/BIP_0034)
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*/
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package blockchain
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