git ssb

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/**
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 * This implements the Ethereum Kernel
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 * Kernels must implement two methods `codeHandler` and `callHandler` (and `linkHandler` for sharding)
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 * The Kernel Contract handles the following
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 * - Interprocess communications
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 * - Intializing the VM and exposes ROM to it (codeHandler)
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 * - Expose namespace which VM instance exists and Intializes the Environment (callHandler)
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 * - Provides some built in contract (runTx, runBlock)
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 * - Provides resource sharing and limiting via gas
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 *
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 *   All State should be stored in the Environment.
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 *
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 */
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// The Kernel Exposes this Interface to VM instances it makes
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const Interface = require('./interface.js')
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// The Kernel Stores all of its state in the Environment. The Interface is used
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// to by the VM to retrive infromation from the Environment.
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const Environment = require('./environment.js')
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const DebugInterface = require('./debugInterface.js')
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const Utils = require('./utils.js')
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module.exports = class Kernel {
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  // runs some code in the VM
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  constructor (environment = new Environment()) {
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    this.environment = environment
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  }
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  // handles running code.
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  // NOTE: it assumes that wasm will raise an exception if something went wrong,
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  //       otherwise execution succeeded
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  codeHandler (code, ethInterface = new Interface(new Environment())) {
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    const debugInterface = new DebugInterface(ethInterface.environment)
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    const instance = Wasm.instantiateModule(code, {
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      'ethereum': ethInterface.exportTable,
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      'debug': debugInterface.exportTable,
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      // export this for Rust
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      // FIXME: remove once Rust has proper imports, see https://github.com/ethereum/evm2.0-design/issues/15
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      'spectest': ethInterface.exportTable,
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      // export this for Binaryen
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      // FIXME: remove once C has proper imports, see https://github.com/ethereum/evm2.0-design/issues/16
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      'env': ethInterface.exportTable
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    })
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    ethInterface.setModule(instance)
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    debugInterface.setModule(instance)
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    if (instance.exports.main) {
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      instance.exports.main()
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    }
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    return instance
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  }
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  // loads code from the merkle trie and delegates the message
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  // Detects if code is EVM or WASM
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  // Detects if the code injection is needed
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  // Detects if transcompilation is needed
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  callHandler (address, gaslimit, gasprice, value, data) {
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    var toAccount = this.environment.accounts.get(new Uint8Array(address).toString())
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    if (!toAccount) {
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      throw new Error('Account not found')
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    }
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    // creats a new Kernel
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    const environment = new Environment(data)
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    environment.parent = this
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    const kernel = new Kernel(this, environment)
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    const code = this.environment.state.get(address)
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    //environment.setCallHandler(callHandler)
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    if (!code) {
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      throw new Error('Contract not found')
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    }
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    if (!Utils.isWASMCode(code)) {
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      throw new Error('Not an eWASM contract')
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    }
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    kernel.codeHandler(code, new Interface(environment))
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    // generate new stateroot
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    //this.environment.state.set(address, { stateRoot: stateRoot })
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    return {
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      executionOutcome: 1, // success
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      gasLeft: 0,
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      gasRefunds: 0,
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      returnValue: new ArrayBuffer(),
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      selfDestructAddress: new Uint8Array(),
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      logs: []
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    }
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  }
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  // run tx; the tx message handler
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  runTx (tx, environment = new Environment()) {
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    // verify tx then send to call Handler
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    // - from account has enough balance
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    // - check nonce
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    // - ecrecover
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    // new ethTx(tx).validate(tx)
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    // - reduce balance
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    this.environment = environment
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    // Contract deployment
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    //const isDeployment = tx.data && !tx.to;
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    //if (isDeployment) {
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    //  this.environment.accounts.set(new Uint8Array())
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    //}
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    //
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    // environment.state - the merkle tree
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    // key: address (20 byte, hex string, without 0x prefix)
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    // every path has an account
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    //
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    // { balance, codeHash, stateRoot }
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    //
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    // look up sender
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    let fromAccount = this.environment.accounts.get(new Uint8Array(tx.form).toString())
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    // deduct gasLimit * gasPrice from sender
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    if (fromAccount.balance < (tx.gasLimit * tx.gasPrice)) {
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      throw new Error('Insufficient account balance')
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    }
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    fromAccount.balance -= ts.gasLimit * tx.gasPrice
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    let ret = this.callHandler(tx.to, tx.gasLimit, tx.gasPrice, tx.value, tx.data)
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    // refund gas
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    if (ret.executionOutcome === 1) {
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      fromAccount.balance += (ret.gasLeft + ret.gasRefund) * tx.gasPrice
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    }
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    // save new state?
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    return {
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      returnValue: ret.returnValue,
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      gasLeft: ret.gasLeft,
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      logs: ret.logs
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    }
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  }
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  // run block; the block message handler
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  runBlock (block, environment = new Environment()) {
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    // verify block then run each tx
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    block.tx.forEach((tx) => {
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      this.runTx(tx, environment)
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    })
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  }
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  // run blockchain
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  // runBlockchain () {}
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}
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