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92 lines
2.8 KiB
Markdown
92 lines
2.8 KiB
Markdown
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---
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title: Blockchain Verification
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id: version-0.2.0-chain
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original_id: chain
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---
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Bitcoin-S comes bundled with a rudimentary blockchain verification
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module. This module is currently only released as a library, and not as a binary.
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This is because it (nor the documentation) is not deemed production
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ready. Use at your own risk, and without too much money depending on it.
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## Syncing and verifying block headers
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Using the `chain` module of Bitcoin-S it's possible to
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sync and verify block headers from the Bitcoin blockchain. In this document
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we demonstrate how to do this, while persisting it to disk. We should be
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able to read this chain on subsequent runs, assuming we are connected
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to the same `bitcoind` instance.
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```scala
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import org.bitcoins.chain.blockchain._
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import org.bitcoins.chain.blockchain.sync._
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import org.bitcoins.chain.models._
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import org.bitcoins.rpc.client.common._
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import org.bitcoins.testkit.chain._
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import scala.concurrent._
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implicit val ec = ExecutionContext.global
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// We are assuming that a `bitcoind` regtest node is running the background.
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// You can see our `bitcoind` guides to see how to connect
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// to a local or remote `bitcoind` node.
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import org.bitcoins.rpc.config.BitcoindInstance
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import org.bitcoins.rpc.client.common.BitcoindRpcClient
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val bitcoindInstance = BitcoindInstance.fromDatadir()
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val rpcCli = BitcoindRpcClient(bitcoindInstance)
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// Next, we need to create a way to monitor the chain:
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val getBestBlockHash = ChainTestUtil.bestBlockHashFnRpc(Future.successful(rpcCli))
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val getBlockHeader = ChainTestUtil.getBlockHeaderFnRpc(Future.successful(rpcCli))
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// set a data directory
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import java.nio.file.Files
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val datadir = Files.createTempDirectory("bitcoin-s-test")
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// set the currenet network to regtest
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import com.typesafe.config.ConfigFactory
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val config = ConfigFactory.parseString {
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"""
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| bitcoin-s {
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| network = regtest
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| }
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|""".stripMargin
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}
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import org.bitcoins.chain.config.ChainAppConfig
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implicit val chainConfig = ChainAppConfig(datadir, config)
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// Initialize the needed database tables if they don't exist:
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val chainProjectInitF = chainConfig.initialize()
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val blockHeaderDAO = BlockHeaderDAO()
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val compactFilterHeaderDAO = CompactFilterHeaderDAO()
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val compactFilterDAO = CompactFilterDAO()
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// Now, do the actual syncing:
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val chainHandlerF = ChainHandler.fromDatabase(blockHeaderDAO, compactFilterHeaderDAO, compactFilterDAO)
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val syncedChainApiF = for {
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_ <- chainProjectInitF
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handler <- chainHandlerF
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synced <- ChainSync.sync(handler, getBlockHeader, getBestBlockHash)
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} yield synced
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val syncResultF = syncedChainApiF.flatMap { chainApi =>
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chainApi.getBlockCount.map(count => println(s"chain api blockcount=${count}"))
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rpcCli.getBlockCount.map(count => println(s"bitcoind blockcount=${count}"))
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}
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syncResultF.onComplete { case result =>
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println(s"Sync result=${result}")
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}
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```
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